RFR: Merge openjdk/jdk21u:master

[William Kemper]

Merges tag jdk-21.0.8+2

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Commit messages:
 - 8353190: Use "/native" Run Option for TestAvailableProcessors Execution
 - 8354802: MAX_SECS definition is unused in os_linux
 - 8349501: Relocate supporting classes in security/testlibrary to test/lib/jdk tree
 - 8333680: com/sun/tools/attach/BasicTests.java fails with "SocketException: Permission denied: connect"
 - 8333013: Update vmTestbase/nsk/share/LocalProcess.java to don't use finalization
 - 8320948: NPE due to unreported compiler error

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

Changes: https://git.openjdk.org/shenandoah-jdk21u/pull/193/files
  Stats: 555 lines in 52 files changed: 228 ins; 223 del; 104 mod
  Patch: https://git.openjdk.org/shenandoah-jdk21u/pull/193.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah-jdk21u.git pull/193/head:pull/193

PR: https://git.openjdk.org/shenandoah-jdk21u/pull/193