Revert "Revert "Revert "Revert "sched/fair: Optimize cgroup pick_next_task_fair()""""

This reverts commit a59bcd8d005afba932219c9f2fe6444ffb7cd8e6.
Revert "Revert "Revert "Revert "sched/fair: Optimize find_busiest_queue()""""

This reverts commit 14aa3f4f46f4394b24fd7e584782c197118817f9.