images: Drop enabling sshd.service on Debian/Ubuntu

Updating the openssh-server package while `sshd.service` is enabled
upsets the maintainer script and fails. It also causes `ssh.socket` to
fail as the port is already used.

This leads to image refresh failures whenever the current cloud image
doesn't have the current openssh-server version.

cockpit-project/cockpit#20261 fixed Cockpit's
tests to not assume `sshd.service` everywhere, so this is obsolete.

images/scripts/debian.setup

@@ -4,10 +4,6 @@
 set -ex
 IMAGE="$1"
 
-# Enable ssh if necessary so that we get the "sshd" alias symlink that
-# everything expects.
-systemctl preset ssh
-
 # Enable a console on ttyS0 so that we can log-in via vm-run.
 # and make the boot up more verbose
 sed -i 's/GRUB_CMDLINE_LINUX_DEFAULT/# GRUB_CMDLINE_LINUX_DEFAULT/' /etc/default/grub