RFR: 8371792: Refactor barrier loop tests out of TestIfMinMax

[Galder Zamarreño]

Trivial cleanup to move tests out of a test class whose description does not match these tests

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Commit messages:
 - 8371792: Refactor barrier loop tests out of TestIfMinMax

Changes: https://git.openjdk.org/jdk/pull/28385/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28385&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8371792
  Stats: 123 lines in 2 files changed: 86 ins; 36 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/28385.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28385/head:pull/28385

PR: https://git.openjdk.org/jdk/pull/28385