Enable the xinetd service for reboot

If the Galera container is rebooted, the xinetd service should be
started. Otherwise the haproxy health check will fail and haproxy will
not forward database connections.

Change-Id: Iefa7b72ea1fa6743fb8486af663512c2ffe1c31d

handlers/main.yml

@@ -94,3 +94,4 @@
   service:
     name: xinetd
     state: restarted
+    enabled: true

tasks/galera_post_install.yml

@@ -181,6 +181,15 @@
     dest: "/usr/local/bin/clustercheck"
     mode: "0755"
 
+# TODO: (nicolasbock) This task can be removed in T but is necessary
+# for S and earlier because deployments prior to this change will not
+# have the xinetd service enabled because the handler task runs only
+# for new deployments.
+- name: Enable xinetd service
+  service:
+    name: xinetd
+    enabled: yes
+
 - name: Create mysqlchk config
   template:
     src: "mysqlchk.j2"