Clean up some type annotations in test/jit (#50158)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/50158
Upgrades type annotations from Python2 to Python3
Test Plan: Sandcastle tests
Reviewed By: xush6528
Differential Revision: D25717504
fbshipit-source-id: 9a83c44db02ec79f353862255732873f6d7f885e
