RFR: 8287200: Test java/lang/management/ThreadMXBean/VirtualThreadDeadlocks.java timed out after JDK-8287103

[Leonid Mesnik]

Need to use proper synchronization.

The CyclicBarriers might move the thread to WAITING state but not BLOCKED. So it should not confuse existing checks.

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Commit messages:
 - 8287200

Changes: https://git.openjdk.java.net/jdk/pull/8874/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8874&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8287200
  Stats: 9 lines in 1 file changed: 4 ins; 2 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8874.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8874/head:pull/8874

PR: https://git.openjdk.java.net/jdk/pull/8874