refactor intialize bucket views (#44330)
Summary:
[test all]
Pull Request resolved: https://github.com/pytorch/pytorch/pull/44330
Part of relanding PR #41954, this refactor is to seperate intialize_bucket_views and populate_bucket_views_out, as they are doing different things and called by different callsites as well
ghstack-source-id: 112257271
Test Plan: unit tests
Reviewed By: mrshenli
Differential Revision: D23583347
fbshipit-source-id: a5f2041b2c4f2c2b5faba1af834c7143eaade938
