RFR: 8367476: Shenandoah: Remove use of CollectedHeap::_soft_ref_policy [v2]

[Albert Mingkun Yang]

On Fri, 12 Sep 2025 14:23:35 GMT, Francesco Andreuzzi <fandreuzzi at openjdk.org> wrote:

>> Similarly to what was done in #26496 and #26648, the usages of `CollectedHeap::_soft_ref_policy` in Shenandoah can be replaced with an earlier call to `ShenandoahReferenceProcessor::set_soft_reference_policy`.
>> 
>> This is the last usage of `CollectedHeap::_soft_ref_policy`, so it can be removed.
>> 
>> Passes tier1-2, and tier3_gc_shenandoah.
>
> Francesco Andreuzzi has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - eagerly initialize to always-clear
>  - move to gccause

I have reviewed all non-Shenandoah code.

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Marked as reviewed by ayang (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/27239#pullrequestreview-3217218522