Revert "add nested tensor matmul support (#81957)"
This reverts commit 7bdafed4f10bc3490dac2421a090e59953d03b41.
Reverted https://github.com/pytorch/pytorch/pull/81957 on behalf of https://github.com/osalpekar due to Reverting this in order to revert https://github.com/pytorch/pytorch/pull/80981 cleanly. That diff caused GPU Inference breakage internally
