fix review findings

Signed-off-by: sivchari <shibuuuu5@gmail.com>

Author: sivchari

test/e2e/data/infrastructure-docker/main/bases/cluster-with-topology.yaml

@@ -15,7 +15,7 @@ spec:
   topology:
     classRef:
       name: "quick-start"
-      namespace: '${CLUSTER_CLASS_NAMESPACE:-""}'
+      namespace: '${CLUSTER_CLASS_NAMESPACE:-${NAMESPACE}}'
     version: "${KUBERNETES_VERSION}"
     controlPlane:
       metadata: