Prevent simultaneous logins from multiple users (multi-seat mode)

Because the home directory is mounted via pam_mount using the user's Kerberos ticket,
simultaneous login of two users is not possible.

roles/custom/fvs/tasks/main.yml

@@ -182,8 +182,8 @@
       #SingleClick=false
 
       [KDE Action Restrictions][$i]
-      #action/start_new_session=false
-      #action/switch_user=false
+      action/start_new_session=false
+      action/switch_user=false
       #action/lock_screen=false
 
 - name: Start with empty session by default