RFR: Merge openjdk/jdk21u-dev:master

[William Kemper]

Merges tag jdk-21.0.4+2

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Commit messages:
 - 8314573: G1: Heap resizing at Remark does not take existing eden regions into account
 - 8319376: ParallelGC: Forwarded objects found during heap inspection
 - 8310913: Move ReferencedKeyMap to jdk.internal so it may be shared
 - 8317007: Add bulk removal of dead nmethods during class unloading
 - 8310228: Improve error reporting for uncaught native exceptions on Windows
 - 8309890: TestStringDeduplicationInterned.java waits for the wrong condition
 - 8331639: [21u]: Bump GHA bootstrap JDK to 21.0.3
 - 8328938: C2 SuperWord: disable vectorization for large stride and scale
 - 8310513: [s390x] Intrinsify recursive ObjectMonitor locking
 - 8330011: [s390x] update block-comments to make code consistent
 - ... and 9 more: https://git.openjdk.org/shenandoah-jdk21u/compare/3ab3f52b...93d091ad

The merge commit only contains trivial merges, so no merge-specific webrevs have been generated.

Changes: https://git.openjdk.org/shenandoah-jdk21u/pull/43/files
  Stats: 2980 lines in 80 files changed: 1993 ins; 795 del; 192 mod
  Patch: https://git.openjdk.org/shenandoah-jdk21u/pull/43.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah-jdk21u.git pull/43/head:pull/43

PR: https://git.openjdk.org/shenandoah-jdk21u/pull/43