RFR: 284233: serviceability/jvmti/vthread/InterruptThreadTest/InterruptThreadTest.java failing in loom repo

[Serguei Spitsyn]

The test has a lack of synchronization.
The fix is to wait for target virtual thread reaching the desired state of execution.
The fix was tested with 100 of mach5 test runs on all platforms.

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Commit messages:
 - 8284233: serviceability/jvmti/vthread/InterruptThreadTest/InterruptThreadTest.java failing in loom repo

Changes: https://git.openjdk.java.net/loom/pull/168/files
 Webrev: https://webrevs.openjdk.java.net/?repo=loom&pr=168&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-284233
  Stats: 9 lines in 1 file changed: 8 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/loom/pull/168.diff
  Fetch: git fetch https://git.openjdk.java.net/loom pull/168/head:pull/168

PR: https://git.openjdk.java.net/loom/pull/168