RFR: 8347842: ThreadPoolExecutor specification discusses RuntimePermission

[Viktor Klang]

Removes ThreadPoolExecutor javadoc which mentions RuntimePermission.

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Commit messages:
 - Removing reference to RuntimePermission in the ThreadPoolExecutor javadoc

Changes: https://git.openjdk.org/jdk/pull/23156/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23156&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8347842
  Stats: 6 lines in 1 file changed: 0 ins; 5 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/23156.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23156/head:pull/23156

PR: https://git.openjdk.org/jdk/pull/23156