injecting domain name from vars/names.yml rather than ansible_domain

roles/postfix/templates/main_cf.j2

@@ -31,7 +31,7 @@ myhostname = {{ ansible_fqdn }}
 alias_maps = hash:/etc/aliases
 alias_database = hash:/etc/aliases
 myorigin =  {{ ansible_fqdn }}
-mydestination = {{ ansible_fqdn }}, localhost.{{ ansible_domain }}, localhost
+mydestination = {{ ansible_fqdn }}, localhost.{{ domain }}, localhost
 relayhost =  {{ smtp_smarthost }}
 mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
 mailbox_size_limit = 0