RFR: 8324647: Invalid test group of lib-test after JDK-8323515

[Jie Fu]

This patch tries to fix the invalid test group definition of lib-test.
Please review.
Thanks.

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Commit messages:
 - 8324647: Invalid test group of lib-test after JDK-8323515

Changes: https://git.openjdk.org/jdk/pull/17558/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17558&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8324647
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/17558.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17558/head:pull/17558

PR: https://git.openjdk.org/jdk/pull/17558