RFR: 8367347: Serial: Refactor CLDScanClosure [v5]

[Francesco Andreuzzi]

> Refactor `CLDScanClosure` so that all CLD logic is encapsulated in the CLD closure, without polluting the oop closure.
> 
> Test: tier1-2, running tier3

Francesco Andreuzzi has updated the pull request incrementally with one additional commit since the last revision:

  _g unused
  
  Co-authored-by: Thomas Schatzl <59967451+tschatzl at users.noreply.github.com>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/27199/files
  - new: https://git.openjdk.org/jdk/pull/27199/files/a8c79778..b8b537e8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27199&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27199&range=03-04

  Stats: 2 lines in 1 file changed: 0 ins; 2 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/27199.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27199/head:pull/27199

PR: https://git.openjdk.org/jdk/pull/27199