remove ops in the __caffe2 namespace (#47318)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/47318
Test Plan: Imported from OSS
Reviewed By: ezyang
Differential Revision: D24714807
Pulled By: bdhirsh
fbshipit-source-id: 7f040c12c0b3a0f322498386f849f693a64d1dcf
