RFR: 8343333: Parallel: Cleanup comment referring Solaris in MutableNUMASpace

[Zhengyu Gu]

A trivial cleanup that removes comment referring Solaris.

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Commit messages:
 - 8343333: Parallel: Cleanup comment referring Solaris in MutableNUMASpace

Changes: https://git.openjdk.org/jdk/pull/21796/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21796&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343333
  Stats: 7 lines in 1 file changed: 0 ins; 2 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/21796.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21796/head:pull/21796

PR: https://git.openjdk.org/jdk/pull/21796