RFR: 8321410: Shenandoah: Remove ShenandoahSuspendibleWorkers flag [v2]

[Roman Kennke]

On Wed, 6 Dec 2023 14:10:01 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> We have flipped `ShenandoahSuspendibleWorkers` to true in [JDK-8305403](https://bugs.openjdk.org/browse/JDK-8305403), and backported it back to 17.0.8. We seem to be in consensus that turning this flag off would likely to cause correctness issues:
>>   https://github.com/openjdk/jdk/pull/13309#discussion_r1160934484
>> 
>> So we might as well remove this flag altogether.
>> 
>> Additional testing:
>>  - [x] `hotspot_gc_shenandoah`
>
> Aleksey Shipilev 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 JDK-8321410-shenandoah-suspendible-workers
>  - Fix

Yes it is a correctness issue, let's get rid of the flag.

I believe that you could also replace ShenandoahSuspendibleThreadSet* with just regular SuspendibleThreadSet*.

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Marked as reviewed by rkennke (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/16984#pullrequestreview-1768538629