Apply suggestions from code review

Co-authored-by: Sergii Tkachenko <[email protected]>

Author: lidizheng

tools/run_tests/xds_k8s_test_driver/framework/xds_url_map_test_resources.py

@@ -139,7 +139,7 @@ def __init__(self, absl_flags: Mapping[str, Any] = None):
             for key in absl_flags:
                 setattr(self, key, absl_flags[key])
         # Pick a client_namespace_suffix if not set
-        if not hasattr(self, 'resource_suffix') or self.resource_suffix is None:  # pylint: disable=access-member-before-definition
+        if getattr(self, 'resource_suffix', None) is None:
             self.resource_suffix = ""
         else:
             raise NotImplementedError(