Test: Added test cases for List Chat Assistants HTTP API (#6792)

### What problem does this PR solve?

cover [list chat
assistant](https://ragflow.io/docs/v0.17.2/http_api_reference#list-chat-assistants)
endpoints

### Type of change

- [x] add test cases

sdk/python/test/test_http_api/test_dataset_mangement/test_list_datasets.py

@@ -331,6 +331,7 @@ class TestDatasetsList:
             params = {"id": dataset_id, "name": name}
 
         res = list_datasets(get_http_api_auth, params=params)
+        assert res["code"] == expected_code
         if expected_code == 0:
             assert len(res["data"]) == expected_num
         else: