fix: remove __func__ from static method access in tests

The _get_response method is a @staticmethod, so it can be called
directly without using __func__. Using __func__ on a static method
accessed through a class raises AttributeError.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: taimo3810

gapic/ads-templates/tests/unit/gapic/%name_%version/%sub/test_%service.py.j2

@@ -1476,8 +1476,8 @@ def test_{{ method_name }}_rest_url_query_params_encoding():
     # when building the URL query string. This tests the urlencode call with safe="$".
     transport = transports.{{ service.rest_transport_name }}(credentials=ga_credentials.AnonymousCredentials)
     method_class = transport.{{ method.transport_safe_name|snake_case }}.__class__
-    # Get the _get_response method from the method class
-    get_response_fn = method_class._get_response.__func__
+    # Get the _get_response static method from the method class
+    get_response_fn = method_class._get_response
 
     mock_session = mock.Mock()
     mock_response = mock.Mock()

gapic/templates/tests/unit/gapic/%name_%version/%sub/test_macros.j2

@@ -1222,8 +1222,8 @@ def test_{{ method_name }}_rest_url_query_params_encoding():
     # when building the URL query string. This tests the urlencode call with safe="$".
     transport = transports.{{ service.rest_transport_name }}(credentials=ga_credentials.AnonymousCredentials)
     method_class = transport.{{ method.transport_safe_name|snake_case }}.__class__
-    # Get the _get_response method from the method class
-    get_response_fn = method_class._get_response.__func__
+    # Get the _get_response static method from the method class
+    get_response_fn = method_class._get_response
 
     mock_session = mock.Mock()
     mock_response = mock.Mock()