RFR: 8339369: G1: TestVerificationInConcurrentCycle.java fails with "Missing rem set entry" when using "-XX:G1RSetUpdatingPauseTimePercent=0 -XX:G1UpdateBufferSize=2"

[Ivan Walulya]

Please review this patch to reset the per region cardsets in the later phases of the full-gc.  This ensures that Remset verification can proceed without considering whether the cardsets are combined or not.

Testing: passes test in the cited in the bug report and Tiers 1-3

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Commit messages:
 - init

Changes: https://git.openjdk.org/jdk/pull/20835/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20835&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339369
  Stats: 3 lines in 2 files changed: 2 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/20835.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20835/head:pull/20835

PR: https://git.openjdk.org/jdk/pull/20835