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

This reverts commit 7f4fbd96a1736854faa03b8439d6d15d07d08bba.
Revert "mutex: restrict mutex spinning to only one task per mutex"

This reverts commit 1e6fc46fd39dccb4f5758479840bf7af1963ebb1.
Revert "mutex: Make more scalable by doing less atomic operations"

This reverts commit 4277d3c8ebdf5158a1f9228f53f7b1d8a3c0c996.