RFR: 8315040: Remove redundant check in WorkerPolicy::parallel_worker_threads

[Lei Zaakjyu]

8315040: Remove redundant check in WorkerPolicy::parallel_worker_threads

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Commit messages:
 - remove redundant check

Changes: https://git.openjdk.org/jdk/pull/17128/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17128&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315040
  Stats: 5 lines in 1 file changed: 0 ins; 4 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/17128.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17128/head:pull/17128

PR: https://git.openjdk.org/jdk/pull/17128