Remove legacy chrooted sftp group 'sftp_users' from o32, o25 and test.mx.

Drop 'create_sftp_group: true' (default false), so the 'Match group
sftp_users' block is no longer rendered into sshd config. The (empty)
group sftp_users was removed on the hosts.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

host_vars/o32.oopen.de/o32-common.yml

@@ -325,8 +325,6 @@ cron_user_entries:
 # vars used by roles/common/tasks/users.yml
 # ---
 
-create_sftp_group: true
-
 extra_system_user:
   - name: ev-stage
     home: /var/www/ev-sites/stage.etventure.com