[jdk20] RFR: 8298296: gc/TestFullGCCount.java fails with "System.gc collections miscounted."

[Kim Barrett]

Please review this change to the gc/TestFullGCCount.java test to account for
the changes in JDK-8297247.  The test was not updated by that change to
account for the new separation by G1 of STW full gc counts from concurrent
cycle counts in the GarbageCollectorMXBean.

To address this, the test has been changed to not be run if using G1 and
-XX:+ExplicitGCInvokesConcurrent.

Testing:
Verified the unmodified test fails when using G1 and +ExplicitGCInvokesConcurrent.
After updating the test, ran it with G1 selected and both with and without
ExplicitGCInvokesConcurrent.  With now suppresses the test, without runs it
successfully.

-------------

Commit messages:
 - disable when using G1 with -XX:+ExplicitGCInvokesConcurrent
 - remove 8298296 from problem list

Changes: https://git.openjdk.org/jdk20/pull/16/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk20&pr=16&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8298296
  Stats: 3 lines in 2 files changed: 2 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk20/pull/16.diff
  Fetch: git fetch https://git.openjdk.org/jdk20 pull/16/head:pull/16

PR: https://git.openjdk.org/jdk20/pull/16