RFR: 8301843: Remove dummy region allocation [v3]

[Thomas Schatzl]

> Hi all,
> 
>   can I have reviews for this imo trivial removal of some debug code?
> 
> This code has never been used by me, and there are better ways imo to get the same effects - see the CR.
> 
> Testing: local compilation, gha
> 
> Thanks,
>   Thomas

Thomas Schatzl has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 10 commits:

 - Merge branch 'master' into submit/8301843-remove-dummy-region-allocation
 - initial version
 - Improve claimer
 - fix indentation :(
 - daholmes review, remove unnecessary change
 - Cleanup
 - Fixes, refactoring
 - Fixes
 - Cleanup
 - initial version
   
   Fix Thread::possibly_parallel_threads_do
   
   refactoring
   
   Initial version, remove retire tlab stuff

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Changes: https://git.openjdk.org/jdk/pull/12433/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12433&range=02
  Stats: 41 lines in 3 files changed: 0 ins; 41 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/12433.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12433/head:pull/12433

PR: https://git.openjdk.org/jdk/pull/12433