Revert "mutex: dynamically disable mutex spinning at high load"

This reverts commit e341b85a17d65cb8061ffd68f71cb46c46b8b8f0.
Revert "mutex: restrict mutex spinning to only one task per mutex"

This reverts commit 32f5c16ffbddb64cf5930a5b06d8c7284ff19d5c.
Revert "mutex: Make more scalable by doing less atomic operations"

This reverts commit 8f5a26910c505219e425726bf839b99af07ae163.