Fix: model list (#15860)

### What problem does this PR solve?

Remove tenant_llm call in rag.

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

api/db/services/tenant_model_service.py

@@ -35,6 +35,15 @@ class TenantModelService(CommonService):
             cls.model.model_name == model_name
         )
 
+    @classmethod
+    @DB.connection_context()
+    def get_by_provider_id_and_instance_id_and_model_type(cls, provider_id, instance_id, model_type):
+        return cls.model.get_or_none(
+            cls.model.provider_id == provider_id,
+            cls.model.instance_id == instance_id,
+            cls.model.model_type == model_type
+        )
+
     @classmethod
     @DB.connection_context()
     def get_models_by_instance_id(cls, instance_id):