Remove get_fail_msg in test_dataloader.test_proper_exit (#40745)
Summary:
Close https://github.com/pytorch/pytorch/issues/40744
Pull Request resolved: https://github.com/pytorch/pytorch/pull/40745
Reviewed By: ezyang
Differential Revision: D22308972
Pulled By: colesbury
fbshipit-source-id: 4b4847e6b926b2614c8b14f17a9db3b0376baabe
