[jdk21u-dev] RFR: 8297692: Avoid sending per-region GCPhaseParallel JFR events in G1ScanCollectionSetRegionClosure

[Roman Marchenko]

This is backport of "[JDK-8297692](https://bugs.openjdk.org/browse/JDK-8297692) Avoid sending per-region GCPhaseParallel JFR events in G1ScanCollectionSetRegionClosure"

Several conflicts related to different class names were resolved in `src/hotspot/share/gc/g1/g1YoungCollector.cpp`.

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Commit messages:
 - Backport a73226b18e274c44171021760e9eb05bc4a8b711

Changes: https://git.openjdk.org/jdk21u-dev/pull/1775/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1775&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8297692
  Stats: 162 lines in 3 files changed: 84 ins; 52 del; 26 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1775.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1775/head:pull/1775

PR: https://git.openjdk.org/jdk21u-dev/pull/1775