Revert "Implement custom thread numbering for POSIX"
Superseded by #25300
This reverts commit d806ad4a3dcf7308147e1a243092d22091560d7d.
As discussed on IRC, this is a temporary patch to fix #23709 (closed) until we can fix it properly.
This reverts commit d806ad4a3dcf7308147e1a243092d22091560d7d.
As discussed on IRC, this is a temporary patch to fix #23709 (closed) until we can fix it properly.