[PyTorch] Migrate copy_ to borrow input/output (#56031)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56031
Copy kernels just immediately do the copy; borrowing should
be fine.
ghstack-source-id: 127409719
Test Plan: CI, review
Reviewed By: ezyang, walterddr
Differential Revision: D27768310
fbshipit-source-id: 7651731fd3dea14adbdb3fef95a6d67c02175508
