Revert "[compiled autograd] support custom ops backed by c++ autograd::Function (#120681)"
This reverts commit d27509c384c9847cd2ac1f5d63ec143704b50591.
Reverted https://github.com/pytorch/pytorch/pull/120681 on behalf of https://github.com/xmfan due to breaking internal builds, see D54707287 ([comment](https://github.com/pytorch/pytorch/pull/120681#issuecomment-1989542344))
