RFR: CODETOOLS-7903471: add test for virtual thread executor

[Sergey Kuksenko]

Add test for virtual thread executor

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Commit messages:
 - CODETOOLS-7903471: add test for virtual thread executor

Changes: https://git.openjdk.org/jmh/pull/103/files
 Webrev: https://webrevs.openjdk.org/?repo=jmh&pr=103&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903471
  Stats: 202 lines in 1 file changed: 202 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jmh/pull/103.diff
  Fetch: git fetch https://git.openjdk.org/jmh.git pull/103/head:pull/103

PR: https://git.openjdk.org/jmh/pull/103