Remove `create_stubs: false` from droiddoc

`create_stubs: false` is the default behavior in soong as of
https://r.android.com/1380730

Test: m ahat-docs
Bug: 144248501
Bug: 143136634
Change-Id: If571c37c44af99988d8efac1f34a7a4d1bd7df20
diff --git a/tools/ahat/Android.bp b/tools/ahat/Android.bp
index 6ee12b1..20e5006 100644
--- a/tools/ahat/Android.bp
+++ b/tools/ahat/Android.bp
@@ -33,7 +33,6 @@
         ":ahat-docs-stubs",
     ],
     custom_template: "droiddoc-templates-sdk",
-    create_stubs: false,
 }
 
 // --- ahat.jar ----------------