RFR: Merge openjdk/jdk21u:master

[William Kemper]

Merges tag jdk-21.0.9+4

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Commit messages:
 - 8325397: sun/java2d/Disposer/TestDisposerRace.java fails in linux-aarch64
 - 8353126: Open source events tests batch1
 - 8352860: Open source events tests batch0
 - 8348135: Fix couple of problem listing entries in test/hotspot/jtreg/ProblemList-Virtual.txt
 - 8352677: Opensource JMenu tests - series2
 - 8185429: [macos] After a modal dialog is closed, no window becomes active
 - 8357285: JSR166 Test case testShutdownNow_delayedTasks failed
 - 8341370: Test java/awt/Frame/ShapeNotSetSometimes/ShapeNotSetSometimes.java fails intermittently on macOS-aarch64
 - 8346255: java/lang/management/ThreadMXBean/VirtualThreadDeadlocks.java finds no deadlock
 - 8353847: Remove extra args to System.out.printf in open/test/jdk/java/net/httpclient tests
 - ... and 237 more: https://git.openjdk.org/shenandoah-jdk21u/compare/54f20959...3949aae8

The webrev contains the conflicts with master:
 - merge conflicts: https://webrevs.openjdk.org/?repo=shenandoah-jdk21u&pr=215&range=00.conflicts

Changes: https://git.openjdk.org/shenandoah-jdk21u/pull/215/files
  Stats: 39746 lines in 807 files changed: 22040 ins; 13897 del; 3809 mod
  Patch: https://git.openjdk.org/shenandoah-jdk21u/pull/215.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah-jdk21u.git pull/215/head:pull/215

PR: https://git.openjdk.org/shenandoah-jdk21u/pull/215