samba-dc: Decrease Samba log level

The default log level (3) produces too much output and quickly fills the
`/var/log` volume on the domain controllers.

group_vars/samba-dc.yml

@@ -3,6 +3,8 @@ samba_server_role: active directory domain controller
 samba_options:
 - idmap_ldb:use rfc2307: 'yes'
 
+samba_dc_log_level: 1
+
 samba_shares:
 - name: sysvol
   path: /var/lib/samba/sysvol