RFR: 8306436: Rename PSS*:_n_workers to PSS*:_num_workers

[Thomas Schatzl]

Hi all,

  please review this rename of the `_n_workers` member to `_num_workers` since the latter uses the more common prefix for amounts of things.

Testing: gha

Thanks,
  Thomas

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Commit messages:
 - Rename PSS*:_n_workers to PSS*:_num_workers

Changes: https://git.openjdk.org/jdk/pull/13531/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13531&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306436
  Stats: 19 lines in 2 files changed: 2 ins; 0 del; 17 mod
  Patch: https://git.openjdk.org/jdk/pull/13531.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13531/head:pull/13531

PR: https://git.openjdk.org/jdk/pull/13531