RFR: 8314100: G1: Improve collection set candidate selection code [v3]

[Ivan Walulya]

On Fri, 18 Aug 2023 11:48:58 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

>> Hi all,
>> 
>>   discussions during review of [JDK-8140326](https://bugs.openjdk.org/browse/JDK-8140326) indicated that he code surrounding selecting candidates after marking/rebuild for the collection set could be improved.
>> 
>> Testing: gha
>> 
>> Thanks,
>>   Thomas
>
> Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:
> 
>   ayang review

Marked as reviewed by iwalulya (Reviewer).

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

PR Review: https://git.openjdk.org/jdk/pull/15243#pullrequestreview-1584704655