[jdk21u-dev] RFR: 8310066: Improve test coverage for JVMTI GetThreadState on carrier and mounted vthread

[Goetz Lindenmaier]

This is a test added later for a fix made in 21. I think we should have this in 21, too.

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Commit messages:
 - Backport 15195e6018c104cbeca0f387ae18bff106792908

Changes: https://git.openjdk.org/jdk21u-dev/pull/1782/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1782&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310066
  Stats: 543 lines in 2 files changed: 543 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1782.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1782/head:pull/1782

PR: https://git.openjdk.org/jdk21u-dev/pull/1782