Revert D27572158: [torchelastic] Make sure torchelastic mp wait for queue to be drained before finishing the process
Test Plan: revert-hammer
Differential Revision:
D27572158 (https://github.com/pytorch/pytorch/commit/e9c6a511005c2dead0f446de548e875c7fe86ae7)
Original commit changeset: 9a360468acc9
fbshipit-source-id: 29f7e2cba3e134bc81fb31b7e1dfceb7c1f9d734
