Lift rpc_timeout to RpcAgent, for other RpcAgents to reuse. (#29341)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/29341
So that other RpcAgent could use this timeout setting as well.
ghstack-source-id: 93481902
Differential Revision: D5681951
fbshipit-source-id: 569c768dc342e8a2d9faf142ceccf696e12e41dc
