Back out "[pytorch][PR] Merge CUDA Streams and Events" (#54996)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/54996
Original commit changeset: 45d9fee9a582
Test Plan: CI
Reviewed By: jspark1105
Differential Revision: D27444718
fbshipit-source-id: deb627230817923eaf84ade50ecb14bfbce4e779
