Register cummaxmin_backward, cumprod_backward as operators (#44410)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/44410
See #44052 for context. One of the cumprod_backward overloads was unused
so I just deleted it.
Test Plan: - `pytest test/test_autograd.py -v`
Reviewed By: mrshenli
Differential Revision: D23605503
Pulled By: zou3519
fbshipit-source-id: f9c5b595e62d2d6e71f26580ba96df15cc9de4f7
