fix(proxy): inline /model_group/info into llm_api_routes

A named enum member is a mutable class attribute, which adds one RUF012
violation and trips the strict-rule budget gate. The grant is a single
path, so inline it in the union instead

litellm/proxy/_types.py

@@ -567,10 +567,6 @@ class LiteLLMRoutes(enum.Enum):
         "/v1/model/info",
     ]
 
-    model_group_info_routes = [
-        "/model_group/info",
-    ]
-
     llm_api_routes = (
         openai_routes
         + anthropic_routes
@@ -582,7 +578,7 @@ class LiteLLMRoutes(enum.Enum):
         + litellm_native_routes
         + list(agent_inference_routes)
         + model_info_routes
-        + model_group_info_routes
+        + ["/model_group/info"]
     )
     info_routes = [
         "/key/info",