Revert "Fix bug in NodeScheduler"

This reverts commit 25f921fb81be4d23a68e52634ed763568188df05.

The scheduler changes can result in smaller queries being starved
by bigger queries due to the introduction of global per-node queues.
Reverting for now so we can release. We'll revisit later.
Revert "Remove SetThreadName as it consumes a significant amount of cpu time"

This reverts commit 771756b8b7c302bb679642a8d114053991b95581.

The scheduler changes can result in smaller queries being starved
by bigger queries due to the introduction of global per-node queues.
Reverting for now so we can release. We'll revisit later.
Revert "Global split assignment"

This reverts commit 8cbfd758dd0f09aaee763b9cb41303e4dde6cb9e.

The scheduler changes can result in smaller queries being starved
by bigger queries due to the introduction of global per-node queues.
Reverting for now so we can release. We'll revisit later.
Remove reference to scheduler improvements from release notes