Revert "scheduler: Re-compute time-average nr_running on read"

This reverts commit 01b406e614c98dae249b9375cd515b82118477ed.
Revert "proc: enhance time-average nr_running stats"

This reverts commit d12b93fee2a023ea5bfc9e7e452efbbf94e5c55f.
Revert "scheduler: compute time-average nr_running per run-queue"

This reverts commit 054f5bab6abbc616f216eefab184eb79b679123d.