[PyTorch][easy] Deduplicate memory planner creation code (#67265)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/67265
Avoid repeating this initialization code.
ghstack-source-id: 141585971
Test Plan: CI
Reviewed By: hlu1
Differential Revision: D31933368
fbshipit-source-id: 6342ae9bb82c4d152a427bad142470c3d162de69
