Rename job to be py2-setup-validate-errormsg (#56593)
Summary:
This should clarify its purpose, which is:
> to make sure that we give an appropriate error message when someone tries to use python2
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56593
Test Plan: CI.
Reviewed By: gchanan
Differential Revision: D27913086
Pulled By: samestep
fbshipit-source-id: e7555d5cab5696b19a17824383c92f25f91da2cf
