Disable optimizer for `__setstate__` (#23698)
Summary:
Before calling `__setstate__` when loading a module, we need to disable
the optimizer since the module's type does not match the values on the
stack (all the tensors will be `UndefinedTensor`)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/23698
Pulled By: driazati
Differential Revision: D16690935
fbshipit-source-id: 71e2238fd25cd16271af478ef21a3cf4e514a462
