allow tests to run locally without setting environment variables (#55880)
Summary:
Fixes breakage caused by https://github.com/pytorch/pytorch/issues/55753
Pull Request resolved: https://github.com/pytorch/pytorch/pull/55880
Reviewed By: nikithamalgifb
Differential Revision: D27735299
Pulled By: mruberry
fbshipit-source-id: f8f927f95e4f7fe5f00448ed25d23dac3b7104a4
