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

[Aleksey Shipilev]

> 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

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/16984/files
  - new: https://git.openjdk.org/jdk/pull/16984/files/0370357f..3e0a580e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16984&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16984&range=00-01

  Stats: 31526 lines in 319 files changed: 9148 ins; 21344 del; 1034 mod
  Patch: https://git.openjdk.org/jdk/pull/16984.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16984/head:pull/16984

PR: https://git.openjdk.org/jdk/pull/16984