conf: Don't generate machine names with a dot

conf: Don't generate machine names with a dot

According to the linked BZ, machined expects either valid
hostname or valid FQDN (see systemd commit
v239-3092-gd65652f1f2). While in case of multiple dots, a
trailing one doesn't violate FQDN, it does violate the rule in
case of something simple, like "domain.". But it's safe to remove
it in both cases.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1808499
Fixes: 45464db8ba502764cf37ec9335770248bdb3d9a8
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>