Revert D33694867: Fix persistent worker exits before pin_memory thread
Test Plan: revert-hammer
Differential Revision:
D33694867 (https://github.com/pytorch/pytorch/commit/e2191e7084af2aae39ca52720bc2f71e7ea51e7a)
Original commit changeset: 0847f4d424a0
Original Phabricator Diff: D33694867 (https://github.com/pytorch/pytorch/commit/e2191e7084af2aae39ca52720bc2f71e7ea51e7a)
fbshipit-source-id: 5f28616700d8647cbe468a9e300724a7f0c6cc15
(cherry picked from commit 3d8125ba6d669e19efebd9c76b0bd19499a1583e)
