test(kubeflow): mock kube clients in cleanup-noop test

test_cleanup_noop_without_workdir_pvc constructed a KubeflowExecutor
without the mock_k8s_clients fixture, so __post_init__ ran the real
config.load_kube_config()/load_incluster_config() and crashed in CI
(no kubeconfig). Request the fixture like every other executor test.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: oliver könig <okoenig@nvidia.com>

Author: ko3n1g

test/core/execution/test_kubeflow.py

@@ -510,7 +510,7 @@ def test_cleanup_pulls_results_when_workdir_pvc(self, workdir_executor):
             workdir_executor.cleanup("exp-id___trainer___test-job")
         mock_pull.assert_called_once_with("test-job")
 
-    def test_cleanup_noop_without_workdir_pvc(self):
+    def test_cleanup_noop_without_workdir_pvc(self, mock_k8s_clients):
         e = KubeflowExecutor(image="test:latest")
         with patch.object(e, "pull_results") as mock_pull:
             e.cleanup("exp-id___trainer___test-job")