loadbalancer: fail on failed "Wait for backup * to start" handlers

If a faulty HAProxy/ProxySQL configuration is applied and the backup
HAProxy/ProxySQL containers have not been successfully restarted, a
hard stop must be performed so that the master HAProxy/ProxySQL
container with the faulty configuration is not also stopped and restarted.

Change-Id: I82b2003e90993df5227c58b5511adcc391742bda

ansible/roles/loadbalancer/handlers/main.yml

@@ -122,6 +122,7 @@
   wait_for:
     host: "{{ api_interface_address }}"
     port: "{{ haproxy_monitor_port }}"
+  any_errors_fatal: true
 
 - name: Start backup proxysql container
   vars:
@@ -156,6 +157,7 @@
   wait_for:
     host: "{{ api_interface_address }}"
     port: "{{ proxysql_admin_port }}"
+  any_errors_fatal: true
 
 - name: Start backup keepalived container
   vars: