RFR: 8325643: G1: Refactor G1FlushHumongousCandidateRemSets [v2]

[Albert Mingkun Yang]

> Simple refactoring to ensure both paths are checked regarding remset status.

Albert Mingkun Yang has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:

 - Merge branch 'master' into g1-eager-reclaim
 - review
 - review
 - if-else
 - g1-eager-reclaim

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17808/files
  - new: https://git.openjdk.org/jdk/pull/17808/files/72e47bd5..ad79a9fb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17808&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17808&range=00-01

  Stats: 8898 lines in 341 files changed: 3145 ins; 3976 del; 1777 mod
  Patch: https://git.openjdk.org/jdk/pull/17808.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17808/head:pull/17808

PR: https://git.openjdk.org/jdk/pull/17808