[experimental] use EXCEPT_FOR env to suppress CPU tests from GPU RE (#108672)
Summary:
[experimental] use EXCEPT_FOR env to suppress CPU tests from GPU RE -- alternative implementation to D48997976 using preexisting PYTORCH_TESTING_DEVICE_EXCEPT_FOR facility and building remaining logic (for assert-positive listers like test_transformers) on top of that.
Goal: save ~100 GPU (10% of capacity), enables us to fund more aggressive PyPer unit testing on GPU RE
Test Plan: sandcastle, github
Differential Revision: D48998582
Pull Request resolved: https://github.com/pytorch/pytorch/pull/108672
Approved by: https://github.com/bertmaher
