[jdk22] RFR: 8322237: Heap dump contains duplicate thread records for mounted virtual threads

[Alex Menkov]

Hi all,

This pull request contains a backport of commit [dd8ae616](https://github.com/openjdk/jdk/commit/dd8ae616437398f957f9b4f09cf2c7f1d0bd0938) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.

The commit being backported was authored by Alex Menkov on 9 Jan 2024 and was reviewed by David Holmes and Serguei Spitsyn.

Thanks!

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Commit messages:
 - Backport dd8ae616437398f957f9b4f09cf2c7f1d0bd0938

Changes: https://git.openjdk.org/jdk22/pull/60/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk22&pr=60&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8322237
  Stats: 35 lines in 2 files changed: 33 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk22/pull/60.diff
  Fetch: git fetch https://git.openjdk.org/jdk22.git pull/60/head:pull/60

PR: https://git.openjdk.org/jdk22/pull/60