reenable rand_like fusion when there is no broadcast (#16087)

reenable rand_like fusion when there is no broadcast (#16087)

Summary:
Reenables rand_like fusion if no tensor is broadcasted in the fusion group. This is a sufficient but not necessary condition for fused rand_like to produce correct results, and it has an unpleasant side effect of falling back to non-fused path if rand_like was optimistically included in the fusion group, but there is a broadcast in the fusion group not necessarily related to rand_like. E.g. before this PR, if the network had (biasAdd -> relu -> dropout), fuser could fuse biasAdd and relu, now it will try fusing the whole thing (if dropout is expressed via rand_like) and fall back every time.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16087

Differential Revision: D13720232

Pulled By: zou3519

fbshipit-source-id: 1e19203bec4a59257bfc7078b054a19f00fab4ad