RFR: 7903914: JMH: Faster integration tests

[Aleksey Shipilev]

Current GHA runs one batch of integration tests in >10 minutes. We need to see if there are opportunities to speed them up without reducing the coverage.

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jmh/pull/148/files
  Webrev: https://webrevs.openjdk.org/?repo=jmh&pr=148&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903914
  Stats: 16 lines in 11 files changed: 3 ins; 0 del; 13 mod
  Patch: https://git.openjdk.org/jmh/pull/148.diff
  Fetch: git fetch https://git.openjdk.org/jmh.git pull/148/head:pull/148

PR: https://git.openjdk.org/jmh/pull/148