dropout update in autodiff (#66273)
Summary:
1. Unifies dropout op in autodiff
2. Removes dropout inference support in autodiff
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66273
Reviewed By: jbschlosser, gmagogsfm
Differential Revision: D31580382
Pulled By: eellison
fbshipit-source-id: 41d15da99bf4ce6c47cc335a4156c4a1c9705a70
