ipatests: Cleanup 'collect_logs' decorator
    
    The last usage of 'collect_logs' decorator has been removed
    in 1d70ce850e9. So, it could be safely removed.
    
    Fixes: https://pagure.io/freeipa/issue/8265
    Signed-off-by: Stanislav Levin <slev@altlinux.org>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>