[jdk25] RFR: 8361602: [TESTBUG] serviceability/HeapDump/UnmountedVThreadNativeMethodAtTop.java deadlocks on exception

[Richard Reingruber]

This pull request contains a backport of commit [917d0182](https://github.com/openjdk/jdk/commit/917d0182cb5ea6066afd396381ca4650371e64b0) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.

It moves the notify() call to the finally block to avoid the deadlock in join() if verifyHeapDump(dumpFile) throws an exception. It also wraps the wait into a loop to protect against spurious wake up.

The commit being backported was authored by Richard Reingruber on 12 Jul 2025 and was reviewed by Chris Plummer, Christoph Langer and David Holmes.

Testing was done with fastdebug and release builds on the main platforms and also on Linux/PPC64le and AIX.

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Commit messages:
 - Backport 917d0182cb5ea6066afd396381ca4650371e64b0

Changes: https://git.openjdk.org/jdk/pull/26279/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26279&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8361602
  Stats: 10 lines in 1 file changed: 5 ins; 1 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/26279.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26279/head:pull/26279

PR: https://git.openjdk.org/jdk/pull/26279