cleanup torch.testing namespace (#72708)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/72708
Test Plan: Imported from OSS
Reviewed By: mrshenli
Differential Revision: D34457728
Pulled By: mruberry
fbshipit-source-id: 8e017d2a1fd45f69533d1cdfd906d242b6b3ee68
(cherry picked from commit 8a2333a5668e64b45ab8cbc195e5e06383d49c0a)
