RFR: 8365034: G1: Remove num_groups_selected in G1CollectionSet::select_candidates_from_optional_groups as it is unnecessary [v3]

[Thomas Schatzl]

> Hi all,
> 
>   please review this removal of the local `num_selected_regions` from `G1CollectionSet::select_candidates_from_optional_groups()` - the same information is maintained within the local `selected_groups` list.
> 
> Testing: gha
> 
> Thanks,
>   Thomas

Thomas Schatzl has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 12 commits:

 - Merge branch 'master' into 8365034-remove-unnecessary-num_selected_regions
 - * ayang review
 - Merge branch '8364934-g1collectionset-renaming' into 8365034-remove-unnecessary-num_selected_regions
 - Merge branch 'master' into 8364934-g1collectionset-renaming
 - Merge branch 'master' into 8364934-g1collectionset-renaming
 - * one more renaming: prepare_groups_for_scan() -> prepare_for_scan()
 - Merge branch '8364925-improve-program-flow-inc-cset' into 8364934-g1collectionset-renaming
 - * ayang review
 - 8365034
   
   Hi all,
   
     please review this removal of the local `num_selected_regions` from `G1CollectionSet::select_candidates_from_optional_groups()` - the same information is maintained within the local `selected_groups` list.
   
   Testing: gha
   
   Thanks,
     Thomas
 - 8364934
   
   Hi all,
   
     please review this renaming of various members of `G1CollectionSet` to
   
   - use the same prefixes
   - remove unnecessary prefixes (`collection_set`)
   - fix some documentation
   
   Testing: gha
   
   Thanks,
     THoams
 - ... and 2 more: https://git.openjdk.org/jdk/compare/fb651fd6...131c4d63

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

Changes: https://git.openjdk.org/jdk/pull/26674/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26674&range=02
  Stats: 9 lines in 1 file changed: 0 ins; 7 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/26674.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26674/head:pull/26674

PR: https://git.openjdk.org/jdk/pull/26674