cl/428815347: ghOSt: Implement TaskDeparted in non-PrioTable-based schedulers
cl/428815347: ghOSt: Implement TaskDeparted in non-PrioTable-based schedulers

Tested: for i in {1..100}; do ./simple_exp; done

google/ghost-userspace,google/ghost-userspace,google/ghost-userspace,google/ghost-userspace