Remove `balance` and `devices` parameter from Pipe. (#46804)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/46804
As per our design in https://github.com/pytorch/pytorch/issues/44827,
changign the API such that the user places modules on appropriate devices
instead of having a `balance` and `devices` parameter that decides this.
This design allows us to use RemoteModule in the future.
ghstack-source-id: 116479842
Test Plan: waitforbuildbot
Reviewed By: mrshenli
Differential Revision: D24524219
fbshipit-source-id: 9973172c2bb7636572cdc37ce06bf8368638a463
