Revert "[MPS] Add `group_norm[fwd+backward]` and `mean_var` (#91190)"
This reverts commit 371716eb36b7447003f1643f14ff1c5998a9302c.
Reverted https://github.com/pytorch/pytorch/pull/91190 on behalf of https://github.com/kit1980 due to Broke test_correct_module_names because of underscore _ops
