Revert D31389480: [pytorch][PR] Allow external CUDA streams to be set as current
Test Plan: revert-hammer
Differential Revision:
D31389480 (https://github.com/pytorch/pytorch/commit/61f0bb70c1cd63a2dd396c5774d055551914e492)
Original commit changeset: 2b2f40e5452c
fbshipit-source-id: c6631e51abcf3819732f981f646cb77b91569c7d
