Remove legacy way of exposing caffe2 operators to PyTorch (#17742)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/17742
This path isn't used anymore, and is incompatible with the changes stacked on top of this diff.
Removing it.
cc bwasti to check and confirm these can really be deleted
Reviewed By: ezyang
Differential Revision: D14362426
fbshipit-source-id: 32cdc19f28c2a981ae1e204901420998367ee588
