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

This reverts commit 808b74ab54766c9f61f933f0bcef3748cbf0cee7.
Revert "mutex: restrict mutex spinning to only one task per mutex"

This reverts commit 92657b7c601ae0cdad179293ae0576c2c5f0daa9.
Revert "mutex: Make more scalable by doing less atomic operations"

This reverts commit 61149001f339f9d513d1522a84df2096d78f5794.