fix the CI job for onnx (#22946)
Summary:
ONNX uses virtualenv, and PyTorch doesn't. So --user flag is causing problems in ONNX ci...
Fixing it by moving it to pytorch only scripts. And will install ninja in onnx ci separately.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/22946
Reviewed By: bddppq
Differential Revision: D16297781
Pulled By: houseroad
fbshipit-source-id: 52991abac61beaf3cfbcc99af5bb1cd27b790485
