remove unused migration code

Author: geetu040

openml/testing.py

@@ -15,8 +15,6 @@
 import requests
 
 import openml
-from openml._api import API_REGISTRY, HTTPCache, HTTPClient, MinIOClient, ResourceAPI
-from openml.enums import APIVersion, ResourceType
 from openml.exceptions import OpenMLServerException
 from openml.tasks import TaskType
 
@@ -55,11 +53,6 @@ class TestBase(unittest.TestCase):
     logger = logging.getLogger("unit_tests_published_entities")
     logger.setLevel(logging.DEBUG)
 
-    # migration-specific attributes
-    cache: HTTPCache
-    http_clients: dict[APIVersion, HTTPClient]
-    minio_client: MinIOClient
-
     def setUp(self, n_levels: int = 1, tmpdir_suffix: str = "") -> None:
         """Setup variables and temporary directories.
 
@@ -111,13 +104,6 @@ def setUp(self, n_levels: int = 1, tmpdir_suffix: str = "") -> None:
         self.connection_n_retries = openml.config.connection_n_retries
         openml.config.set_retry_policy("robot", n_retries=20)
 
-        self.cache = HTTPCache()
-        self.http_clients = {
-            APIVersion.V1: HTTPClient(api_version=APIVersion.V1),
-            APIVersion.V2: HTTPClient(api_version=APIVersion.V2),
-        }
-        self.minio_client = MinIOClient()
-
     def use_production_server(self) -> None:
         """
         Use the production server for the OpenML API calls.
@@ -284,11 +270,6 @@ def _check_fold_timing_evaluations(  # noqa: PLR0913
                         assert evaluation >= min_val
                         assert evaluation <= max_val
 
-    def _create_resource(self, api_version: APIVersion, resource_type: ResourceType) -> ResourceAPI:
-        http_client = self.http_clients[api_version]
-        resource_cls = API_REGISTRY[api_version][resource_type]
-        return resource_cls(http=http_client, minio=self.minio_client)
-
 
 def check_task_existence(
     task_type: TaskType,