Delete stub file to enable mypy check (#4649) (#88701)
Summary:
X-link: https://github.com/facebookresearch/detectron2/pull/4649
Context in https://fburl.com/4irjskbe
This change deletes distributed.pyi, so that lintrunner will run mypy on distributed.py for typing check.
Test Plan: CI
Differential Revision: D41028360
Pull Request resolved: https://github.com/pytorch/pytorch/pull/88701
Approved by: https://github.com/zhaojuanmao
