Add missing galera.upgrade.post state

PROD-33293

Change-Id: I67e9cea702ec7e6afd5a3292e4fc454231fe14f1
diff --git a/galera/upgrade/post/init.sls b/galera/upgrade/post/init.sls
new file mode 100644
index 0000000..cda9fcb
--- /dev/null
+++ b/galera/upgrade/post/init.sls
@@ -0,0 +1,6 @@
+{%- from "galera/map.jinja" import master,slave with context %}
+
+galera_post:
+  test.show_notification:
+    - name: "dump_message_post-upgrade"
+    - text: "Running galera.upgrade.post"