Revert D18549919: Add `RpcAgentOptions` struct type, which bundles different required arguments for different `RpcAgent`s
Test Plan: revert-hammer
Differential Revision:
D18549919
Original commit changeset: b9f3f1a41d1f
fbshipit-source-id: 2d5e578d18c0725b59eb99a0e942fbf7fe3341ee