Revert "masked logsumexp/logaddexp"
This reverts commit 49e15b578a1019c5a6e045d3fc184e881e994535.
Reverted https://github.com/pytorch/pytorch/pull/77876 on behalf of https://github.com/suo due to This broke master by adding a weird file, you attempted to delete it by committing on top of the head branch but that's not how ghstack works
