Revert "[cuDNN] (re-open) Enable cuDNN Frontend v8 API by Default (#87669)"
This reverts commit 3c6bddc3f6347ce7d1ed33aee94cdaa953cbc387.
Reverted https://github.com/pytorch/pytorch/pull/87669 on behalf of https://github.com/eqy due to investigating convnext benchmark regressions
