[Join][BE] Fix typo; remove obsolete method (#72886)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/72886
**Test Plan**
Searching for `_schedule_shadow_all_reduce_for_fwd_pass` shows that it is defined but never used.
Test Plan: Imported from OSS
Reviewed By: mrshenli
Differential Revision: D34255651
Pulled By: awgu
fbshipit-source-id: 205a0325c2cdc05e127a183cb86fa2fc2e0db99d
(cherry picked from commit 4492f03a3f37c01efa281a6d09a7e3b673cb1139)
