Integrated: 8329720: Gtest failure printing markword after JDK-8325303

[David Holmes]

Trivial test fix that changes `is_neutral` to `is_unlocked`.

Testing: locally, tier1 (sanity)

Thanks

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Commit messages:
 - 8329720: Gtest failure printing markword after JDK-8325303

Changes: https://git.openjdk.org/jdk/pull/18641/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18641&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8329720
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/18641.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18641/head:pull/18641

PR: https://git.openjdk.org/jdk/pull/18641