Merge "Compatible with ubuntu 18.04"

ansible/roles/haproxy/templates/haproxy.json.j2

+{% set haproxy_cmd='/usr/sbin/haproxy -W -db' if kolla_base_distro in ['ubuntu']  else '/usr/sbin/haproxy-systemd-wrapper' %}
 {
-    "command": "/usr/sbin/haproxy-systemd-wrapper -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid",
+    "command": "{{ haproxy_cmd }} -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid",
     "config_files": [
         {
             "source": "{{ container_config_directory }}/haproxy.cfg",