replace platform specific CI environment variables with generic ones (#68022)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/59478
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68022
Reviewed By: seemethere
Differential Revision: D32286934
Pulled By: atalman
fbshipit-source-id: 1008938088da56807e85fb5d776abf79f28ef77b
