RFR: 8364423: G1: Refactor G1UpdateRegionLivenessAndSelectForRebuildTask [v3]

[Thomas Schatzl]

> Hi all,
> 
>   please review this refactoring of `G1UpdateRegionLivenessAndSelectForRebuildTask` to remove some code duplication, which makes it simpler to add more common code
> 
> Testing: gha
> 
> Thanks,
>   Thomas

Thomas Schatzl has updated the pull request incrementally with two additional commits since the last revision:

 - * readding blank line too
 - * indentation

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/26574/files
  - new: https://git.openjdk.org/jdk/pull/26574/files/90aa50dd..e0654633

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26574&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26574&range=01-02

  Stats: 6 lines in 1 file changed: 1 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/26574.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26574/head:pull/26574

PR: https://git.openjdk.org/jdk/pull/26574