Ensure keepalived is restarted during upgrade

During upgrade, we stop all slave keepalived containers. However, if the
keepalived container configuration has not changed, we never restart
them.

This change fixes the issue by notifying the restart handler when the
containers are stopped.

Change-Id: Ibe094b0c14a70a0eb811182d96f045027aa02c2a
Closes-Bug: #1836368

ansible/roles/haproxy/tasks/upgrade.yml

@@ -10,6 +10,8 @@
     common_options: "{{ docker_common_options }}"
     name: "keepalived"
   when: kolla_internal_vip_address not in secondary_addresses
+  notify:
+    - Restart keepalived container
 
 - name: Flush handlers
   meta: flush_handlers