Add appropriate error messages for ProcessGroupNCCLTest (#42143)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/42143
Replaces the original makeshift error messages in ProcessGroupNCCLTest
with more appropriate ones.
ghstack-source-id: 108711579
Test Plan: Ran the tests on DevGPU
Reviewed By: mrshenli
Differential Revision: D22778505
fbshipit-source-id: 27109874f0b474a74b09f588cf6e7528d2069702
