move 2ops back to autodiff (#18969)
Summary:
Move these 2 ops back to autodiff to unblock xla CI.
I will leave them for my next PR to cleanup symbolic_variable.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/18969
Differential Revision: D14816811
Pulled By: ailzhang
fbshipit-source-id: dd8a7e133dcad29560d3d1d25691883960117299
