Rewrite ShardedTensor.gather to use dist.gather instead of gather_object (#77272)
gather_object is problematic when used with Tensors as they can unpickle on the wrong
device and lead to deadlocks or spurious failures.
This change introduces a RPC workaround for EFA when initing TensorPipe until
they properly address it.
Fixes #73935
Pull Request resolved: https://github.com/pytorch/pytorch/pull/77272
Approved by: https://github.com/pritamdamania87
