Fix typo in selector (#10994)

roles/kubernetes-apps/ingress_controller/ingress_nginx/templates/svc-ingress-nginx.yml.j2

@@ -20,5 +20,5 @@ spec:
       protocol: TCP
   selector:
     app.kubernetes.io/name: ingress-nginx
-    app.kubernetes.io/port-of: ingress-nginx
+    app.kubernetes.io/part-of: ingress-nginx
 {% endif %}