hack: allow deploying the example app in non-default namespace

hack/example-service-monitoring/teardown

@@ -4,5 +4,9 @@ if [ -z "${KUBECONFIG}" ]; then
     KUBECONFIG=~/.kube/config
 fi
 
-kubectl --kubeconfig="$KUBECONFIG" delete -f manifests/examples/example-app
+if [ -z "${NAMESPACE}" ]; then
+    NAMESPACE=default
+fi
+
+kubectl --namespace "$NAMESPACE" --kubeconfig="$KUBECONFIG" delete -f manifests/examples/example-app