[jdk17u-dev] RFR: 8293492: ShenandoahControlThread missing from hs-err log and thread dump

[Aleksey Shipilev]

Unclean backport to improve Shenandoah and keep implementation on sync.

The backport is not clean, because [JDK-8268855](https://bugs.openjdk.org/browse/JDK-8268855) is not present in JDK 17.

Additional testing: 
 - [ ] Linux x86_64 fastdebug `hotspot_gc_shenandoah`

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Commit messages:
 - Backport 85ec1f8d020cf2a9d7dfcc9ed75e43f0cd61c1f2

Changes: https://git.openjdk.org/jdk17u-dev/pull/1405/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1405&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8293492
  Stats: 18 lines in 3 files changed: 1 ins; 16 del; 1 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1405.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1405/head:pull/1405

PR: https://git.openjdk.org/jdk17u-dev/pull/1405