RFR: 8364254: Serial: Remove soft ref policy update in WhiteBox FullGC [v2]

[Sangheon Kim]

On Mon, 4 Aug 2025 13:49:14 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> Simple removing Serial specific logic in `WB_FullGC`, because Serial full-gc handles white-box full-gc already.
>> 
>> Test: tier1-3
>
> 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 two additional commits since the last revision:
> 
>  - Merge branch 'master' into sgc-whitebox
>  - sgc-whitebox

LGTM

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Marked as reviewed by sangheki (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26528#pullrequestreview-3084933418