Enable python3 on some LUCI builds.

Test migration from python2 to python3.

Change-Id: Ic494a81328951650d71303451fc12a34392901a7
diff --git a/tools/luci/config/generated/cr-buildbucket.cfg b/tools/luci/config/generated/cr-buildbucket.cfg
index 36d660b..d49b81d 100644
--- a/tools/luci/config/generated/cr-buildbucket.cfg
+++ b/tools/luci/config/generated/cr-buildbucket.cfg
@@ -33,6 +33,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "angler-armv7-ndebug"
@@ -53,6 +57,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "angler-armv7-non-gen-cc"
@@ -73,6 +81,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "angler-armv8-debug"
@@ -93,6 +105,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "angler-armv8-ndebug"
@@ -113,6 +129,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "angler-armv8-non-gen-cc"
@@ -133,6 +153,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "bullhead-armv7-gcstress-ndebug"
@@ -153,6 +177,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "bullhead-armv8-gcstress-debug"
@@ -173,6 +201,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "bullhead-armv8-gcstress-ndebug"
@@ -193,6 +225,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "fugu-debug"
@@ -213,6 +249,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "fugu-ndebug"
@@ -233,6 +273,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "host-x86-cms"
@@ -253,6 +297,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "host-x86-debug"
@@ -273,6 +321,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "host-x86-gcstress-debug"
@@ -293,6 +345,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "host-x86-ndebug"
@@ -313,6 +369,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "host-x86-poison-debug"
@@ -333,6 +393,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "host-x86_64-cdex-fast"
@@ -353,6 +417,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "host-x86_64-cms"
@@ -373,6 +441,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "host-x86_64-debug"
@@ -393,6 +465,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "host-x86_64-ndebug"
@@ -413,6 +489,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "host-x86_64-non-gen-cc"
@@ -433,6 +513,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "host-x86_64-poison-debug"
@@ -453,6 +537,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "walleye-armv7-poison-debug"
@@ -473,6 +561,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "walleye-armv8-poison-debug"
@@ -493,6 +585,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
     builders {
       name: "walleye-armv8-poison-ndebug"
@@ -513,6 +609,10 @@
       }
       build_numbers: YES
       service_account: "art-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 10
+      }
     }
   }
 }
diff --git a/tools/luci/config/generated/project.cfg b/tools/luci/config/generated/project.cfg
index 3593573..4844ab4 100644
--- a/tools/luci/config/generated/project.cfg
+++ b/tools/luci/config/generated/project.cfg
@@ -7,7 +7,7 @@
 name: "art"
 access: "group:all"
 lucicfg {
-  version: "1.30.9"
+  version: "1.30.11"
   package_dir: ".."
   config_dir: "generated"
   entry_point: "main.star"
diff --git a/tools/luci/config/main.star b/tools/luci/config/main.star
index 714d652..ec1c88e 100755
--- a/tools/luci/config/main.star
+++ b/tools/luci/config/main.star
@@ -22,6 +22,10 @@
 
 lucicfg.check_version("1.30.9", "Please update depot_tools")
 
+luci.builder.defaults.experiments.set({
+    "luci.recipes.use_python3": 10,
+})
+
 # Use LUCI Scheduler BBv2 names and add Scheduler realms configs.
 lucicfg.enable_experiment("crbug.com/1182002")