Remove FutureMessage from sender ProcessGroupAgent (#50023)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/50023
Test Plan: Imported from OSS
Reviewed By: lw
Differential Revision: D25753217
Pulled By: mrshenli
fbshipit-source-id: 5a98473c17535c8f92043abe143064e7fca4413b
