RFR: 8367240: Parallel: Refactor PSScavengeCLDClosure [v4]

[Albert Mingkun Yang]

> Refactor `PSScavengeCLDClosure` and its "enclosing" `PSScavengeFromCLDClosure` so that all CLD logic is encapsulated in the CLD closure, without polluting the oop closure.
> 
> Test: tier1-3

Albert Mingkun Yang has updated the pull request incrementally with one additional commit since the last revision:

  review

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/27165/files
  - new: https://git.openjdk.org/jdk/pull/27165/files/836002b8..0b3f6136

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27165&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27165&range=02-03

  Stats: 2 lines in 1 file changed: 1 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/27165.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27165/head:pull/27165

PR: https://git.openjdk.org/jdk/pull/27165