Revert "Update sdp dispatch logic to enable fused backward (#89154)"
This reverts commit 2e72ec79823111e8dd8c5e82c5d1b56197cd52d3.
Reverted https://github.com/pytorch/pytorch/pull/89154 on behalf of https://github.com/huydhn due to Sorry for reverting your PR but the new test_sdp_math_gradcheck test breaks periodic slow gradcheck, i.e. https://hud.pytorch.org/pytorch/pytorch/commit/419ef2cdcfe84442de5232739284c6a51a18632f
