[jdk21u] RFR: 8312174: missing JVMTI events from vthreads parked during JVMTI attach

[Man Cao]

This change mitigates JVM crashes and use-after-free bugs in JDK 21. See comments in https://bugs.openjdk.org/browse/JDK-8312174. The patch applies cleanly and passes pre-submit tests.

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Commit messages:
 - Backport fda142ff6cfefa12ec1ea4d4eb48b3c1b285bc04

Changes: https://git.openjdk.org/jdk21u/pull/337/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=337&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8312174
  Stats: 424 lines in 9 files changed: 376 ins; 20 del; 28 mod
  Patch: https://git.openjdk.org/jdk21u/pull/337.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/337/head:pull/337

PR: https://git.openjdk.org/jdk21u/pull/337