Simplify async execution for script calls. (#53204)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/53204
Async execution for script calls in request_callback_impl.cpp had two
similar if-else blocks that were hard to read. This PR simplifies some of the
logic by breaking the logic into resuable components.
ghstack-source-id: 122996440
Test Plan: waitforbuildbot
Reviewed By: mrshenli
Differential Revision: D26788459
fbshipit-source-id: f2818c6251a465936ed75b7bd356b616f0580094
