Intermittent fix for get_user_and_group_users_done
    
    users_get_recv() never returns ENOENT. In general it should return EOK
    in the case no matching user was found. But since I forget to handle a
    SID based filter properly in sdap_get_users_process() an error is
    returned in this case which makes get_user_and_group_users_done() work
    as expected with this patch.
    
    There is an upcoming enhancement to users_get_recv() which I'm planning
    to use for a full fix.