update code to use new json based system prompt for routing (#493)

demos/use_cases/preference_based_routing/arch_config.yaml

@@ -1,7 +1,7 @@
 version: "0.1-beta"
 
 routing:
-  model: archgw-v1-router-model
+  model: arch-router
 
 listeners:
   egress_traffic:
@@ -12,10 +12,15 @@ listeners:
 
 llm_providers:
 
-  - name: archgw-v1-router-model
+  - name: arch-router
+    access_key: $OPENAI_API_KEY
+    provider_interface: arch
+    model: Arch-Router
+
+  - name: gpt-4o-mini
     provider_interface: openai
-    model: cotran2/qwen-4-epoch-2600
-    base_url: http://34.46.85.85:8000/v1
+    access_key: $OPENAI_API_KEY
+    model: gpt-4o-mini
 
   - name: gpt-4o
     provider_interface: openai