Revert "Revert "Revert "sched/fair: Optimize find_busiest_queue()"""

This reverts commit 7d08db66d1b43ef444be002bf18b58cdda02aebf.
Revert "Revert "Revert "sched/fair: Optimize cgroup pick_next_task_fair()"""

This reverts commit 10c6ecfe70a33d86de94614e3063d225265abc4c.