Management UI: link to GitHub Discussions and not the Google group

(cherry picked from commit 28ad764)

Author: michaelklishin

deps/rabbitmq_management/priv/www/js/tmpl/layout.ejs

@@ -47,7 +47,7 @@
     <li><a rel="noopener noreferrer" href="https://www.rabbitmq.com/changelog.html" target="_blank">New releases</a></li>
     <li><a rel="noopener noreferrer" href="https://www.vmware.com/products/rabbitmq.html" target="_blank">Commercial edition</a></li>
     <li><a rel="noopener noreferrer" href="https://www.rabbitmq.com/services.html" target="_blank">Commercial support</a></li>
-    <li><a rel="noopener noreferrer" href="https://groups.google.com/forum/#!forum/rabbitmq-users" target="_blank">Google Group</a></li>
+    <li><a rel="noopener noreferrer" href="https://github.com/rabbitmq/rabbitmq-server/discussions" target="_blank">Discussions</a></li>
     <li><a rel="noopener noreferrer" href="https://rabbitmq.com/discord/" target="_blank">Discord</a></li>
     <li><a rel="noopener noreferrer" href="https://rabbitmq.com/slack/" target="_blank">Slack</a></li>
     <li><a rel="noopener noreferrer" href="https://www.rabbitmq.com/plugins.html" target="_blank">Plugins</a></li>