Mock get_cluster_custom_object in existing httproute test

The GatewayConfig fallback code calls get_cluster_custom_object,
which was previously unmocked in the "no hostname" test cases.
On CI, the unmocked call could return stale data instead of
raising, causing the test to get a URL when it expected None.

Author: kryanbeane

src/codeflare_sdk/ray/cluster/test_cluster.py

@@ -1228,6 +1228,10 @@ def mock_list_empty_routes(group, version, namespace, plural, label_selector=Non
         "kubernetes.client.CustomObjectsApi.list_namespaced_custom_object",
         side_effect=mock_list_empty_routes,
     )
+    mocker.patch(
+        "kubernetes.client.CustomObjectsApi.get_cluster_custom_object",
+        side_effect=Exception("No GatewayConfig"),
+    )
 
     result = _get_dashboard_url_from_httproute("test-cluster", "test-ns")
     assert result is None, (