deprecate device getter from `torch.testing` namespace (#63844)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/63844
Test Plan: Imported from OSS
Reviewed By: H-Huang
Differential Revision: D31141433
Pulled By: mruberry
fbshipit-source-id: a29331278ab99a19e225e2cb357458e3db4f9732