Skip a couple of libcore tests for gcstress config am: 114ac9ae57 am: ce3f131b73

Original change: https://android-review.googlesource.com/c/platform/art/+/2982035

Change-Id: Ic8fda3c168d8e963d6f3e802e364921d6e050aac
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
diff --git a/tools/run-libcore-tests.py b/tools/run-libcore-tests.py
index 72db66c..244f912 100755
--- a/tools/run-libcore-tests.py
+++ b/tools/run-libcore-tests.py
@@ -264,6 +264,8 @@
   "test.java.lang.StrictMath.HypotTests#testAgainstTranslit_shard4",
   "test.java.math.BigDecimal",
   "test.java.math.BigInteger#testConstructor",
+  "test.java.util.TestFormatter",
+  "test.java.util.Collection",
 }
 
 DISABLED_FUGU_TESTS = {