General improvements

templates/admin_my_cnf

 [client]
 user=root
 password={{ mysql_root_password }}
-{% if mysql_default_host is defined and hostvars[mysql_default_host|default(inventory_hostname)]["ssh_tunnel_ports"] is defined %}
+{% if inventory_hostname not in groups["dbserver-mysql"] and mysql_default_host is defined and mysql_default_host != inventory_hostname and hostvars[mysql_default_host|default(inventory_hostname)]["ssh_tunnel_ports"] is defined %}
 host=127.0.0.1
 port={{ hostvars[mysql_default_host|default(inventory_hostname)]["ssh_tunnel_ports"][0]["local"] }}
 {% else %}