RFR: 8322539: Parallel: Remove duplicated methods in PSAdaptiveSizePolicy

[Albert Mingkun Yang]

Trivial removing duplicate code.

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Commit messages:
 - pgc-remove-subclass-duplicate

Changes: https://git.openjdk.org/jdk/pull/17167/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17167&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8322539
  Stats: 47 lines in 3 files changed: 0 ins; 41 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/17167.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17167/head:pull/17167

PR: https://git.openjdk.org/jdk/pull/17167