RFR: 8316115: Parallel: Fix -Wconversion warnings around NUMA node ID

[Albert Mingkun Yang]

Essentially same as https://github.com/openjdk/jdk/pull/15541, but for Parallel.

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Commit messages:
 - pgc-leaf

Changes: https://git.openjdk.org/jdk/pull/15682/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15682&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8316115
  Stats: 14 lines in 2 files changed: 0 ins; 0 del; 14 mod
  Patch: https://git.openjdk.org/jdk/pull/15682.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15682/head:pull/15682

PR: https://git.openjdk.org/jdk/pull/15682