RFR: 8351374: Improve comment about queue.remove timeout in CleanerImpl.run

[Kim Barrett]

Please review this revision of a previously puzzling comment intending to
provide the rationale for a bit of non-obvious code.

-------------

Commit messages:
 - improve comment

Changes: https://git.openjdk.org/jdk/pull/23952/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23952&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8351374
  Stats: 8 lines in 1 file changed: 5 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/23952.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23952/head:pull/23952

PR: https://git.openjdk.org/jdk/pull/23952