Composite compliance for gather_backward (#71766)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/71766
No need for a tensorSubclassLike check here (for functorch at least),
changing the zeros to new_zeros is sufficient.
Test Plan: - tested with functorch
Reviewed By: anjali411
Differential Revision: D33772752
Pulled By: zou3519
fbshipit-source-id: 5779a1c20b032d00a549c58ff905cf768f10467f
(cherry picked from commit a927c664d601d0b1cbbd3cda7dc297364c1d9e94)
