Unify the SDK RPC server and the Admin RPC server into a single endpoint

Unify the SDK RPC server and the Admin RPC server into a single endpoint: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). Operationally this is awkward and I'd like to propose collapsing them into a single RPC server.