[jit] Delete polyfill typing (#27510)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/27510
We could delete polyfill typing bc requirements.txt require user to
install typing as a dependency whether in py2 or py3, so those typing
actually not getting used either ways.
Test Plan: Imported from OSS
Differential Revision: D20673393
fbshipit-source-id: ea5276824c6e275c1f991f8c12329040b0058d2b
