The problem is that `chkconfig dm on' will enable
display manager service on *all* runlevels feasible
without paying any attention to its customary subset
of those; the solution seems just to avoid that.

Note that there's at least one more similar case
with networking services vs runlevels 2 and 3;
it's to be handled either in a similar manner,
or somewhat more generically.

Reported-by: Konstantin Savun and Speccyfighter
Suggested-by: Anton Midyukov <antohami@altlinux.org>
See-also: https://bugzilla.altlinux.org/36967
See-also: https://forum.altlinux.org/index.php?topic=36177.msg340553#msg340553
See-also: https://www.opennet.ru/openforum/vsluhforumID3/117762.html#81