Revert D23216393: Support work.result() to get result tensors for allreduce for Gloo, NCCL backends
Test Plan: revert-hammer
Differential Revision:
D23216393 (https://github.com/pytorch/pytorch/commit/0b2694cd11a1bddecc01121a882baa2ed1b35d37)
Original commit changeset: fed5e37fbabb
fbshipit-source-id: 27fbeb1617066fa3f271a681cb089622027d6689
