[skip ci] Skip debug info on PRs (#58897)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/58897
We don't need to be building debug info on PRs since it's just filling up S3/CircleCI storage with useless 800 MB zips, this flips it so it's only run on master + release branches. See #58898 for CI signal
Also see pytorch/builder counterpart (unlike the last debuginfo PR there is no hard dependency between these two so there won't be any churn on un-rebased PRs): https://github.com/pytorch/builder/pull/778
Test Plan: Imported from OSS
Reviewed By: seemethere, samestep
Differential Revision: D28689413
Pulled By: driazati
fbshipit-source-id: 77a37e84afe492215008d5e023ceab0c24adb33c
