Revert "[sdpa] Fix bottom-right efficient attention when Q exceeds K (#193632)"

This reverts commit a698136933787b7a49fce298c857cc73a65e751d.

Reverted https://github.com/pytorch/pytorch/pull/193632 on behalf of https://github.com/pytorch-auto-revert due to Reverted automatically by pytorch's autorevert, to avoid this behaviour add the tag autorevert: disable ([comment](https://github.com/pytorch/pytorch/pull/193632#issuecomment-5397231391))