[jdk21u] RFR: 8318528: Rename TestUnstructuredLocking test

[Aleksey Shipilev]

Clean backport to sync up tests.

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Commit messages:
 - Backport 3f446c51564e0358d74d4929dc2fa1b9263ac3b2

Changes: https://git.openjdk.org/jdk21u/pull/288/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=288&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8318528
  Stats: 120 lines in 2 files changed: 60 ins; 60 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u/pull/288.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/288/head:pull/288

PR: https://git.openjdk.org/jdk21u/pull/288