fix: move VAD agent creation to RI communication agent

Previously, it was started in main, but it should use values negotiated by the RI communication agent.

ref: N25B-356

src/control_backend/core/config.py

@@ -17,7 +17,6 @@ class ZMQSettings(BaseModel):
     internal_sub_address: str = "tcp://localhost:5561"
     ri_command_address: str = "tcp://localhost:0000"
     ri_communication_address: str = "tcp://*:5555"
-    vad_agent_address: str = "tcp://localhost:5558"
 
 
 class AgentSettings(BaseModel):