[PyTorch] Always update op.current_dtype in TensorIteratorBase::set_output (#55940)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/55940
Simpler way to keep current_dtype up to date than #55689.
ghstack-source-id: 127092676
Test Plan: CI
Reviewed By: ezyang
Differential Revision: D27744064
fbshipit-source-id: 23fccb8b0375f5b790439a9a1c9ac07d5fae391b
