replace platform specific CI environment variables with generic ones (#68133)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/59478
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68133
Reviewed By: saketh-are
Differential Revision: D32401080
Pulled By: atalman
fbshipit-source-id: 057a34a56f8a2d324f4d1ea07da3a09772177897
