RFR: 8305233: G1: Refactor G1ClearCardTableTask [v2]

[Albert Mingkun Yang]

> Simple refactoring for better encapsulation.
> 
> Test: hotspot_gc

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

  Update src/hotspot/share/gc/g1/g1RemSet.cpp
  
  Co-authored-by: Thomas Schatzl <59967451+tschatzl at users.noreply.github.com>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13242/files
  - new: https://git.openjdk.org/jdk/pull/13242/files/50ef70c5..93aa290d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13242&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13242&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/13242.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13242/head:pull/13242

PR: https://git.openjdk.org/jdk/pull/13242