[JIT] Remove Dropout during Frozon Optimization (#51589)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/51589
Dropout operators are only needed in training. Remove them for frozen models.
Test Plan: Imported from OSS
Reviewed By: eellison
Differential Revision: D26214259
fbshipit-source-id: 3ab05869e1e1f6c57498ba62bf40944f7c2189aa
