undercloud: manage mysql user + revoke grant during upgrade

This task is done when bootstraping a new deployment but we also need to
run these commands when upgrading the containerized undercloud so
healthcheck can run mysql commands from mysql user.

Change-Id: Ie77785caba0a1fb8e2058a998b21cc88bc666fd7
Closes-Bug: #1776570

docker/services/database/mysql.yaml

@@ -268,6 +268,13 @@ outputs:
                 fi
               become: true
               when: {get_param: UndercloudUpgrade}
+            # https://bugs.launchpad.net/tripleo/+bug/1776570
+            - name: Manage mysql user for healthcheck and revoke grant
+              shell: |
+                mysql -e "CREATE USER IF NOT EXISTS \`mysql\`@\`localhost\`;"
+                mysql -e "REVOKE ALL PRIVILEGES, GRANT OPTION FROM \`mysql\`@\`localhost\`;"
+              become: true
+              when: {get_param: UndercloudUpgrade}
             - name: Stop and disable mysql service
               when: mariadb_enabled|bool
               service: name=mariadb state=stopped enabled=no