postinst: remove pvebanner call

We have the pvebanner.service in places which ensures this gets
called on boot before the getty target.

Thus this only had an effect if we changed the nodename to IP mapping
_and_ upgraded/reinstalled pve-manager, then switching to another TTY
would show the updated IP. But as this a) is for sure not a common
triggered path and b) a IP change suggest a reboot either way, and if
the user can handle it on their own without a reboot, they should be
able to also handle an outdated /etc/issue until the next reboot.

Also for PVE ontop of plain Debian a reboot is needed, so that the
PVE kernel gets booted, so this shouldn't be an issue ther neither.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

debian/postinst

@@ -105,9 +105,6 @@ EOF
 	deb-systemd-invoke start pvesr.timer >/dev/null || true
     fi
 
-    # rewrite banner
-    test -e /proxmox_install_mode || pvebanner || true
-
     if test -z "$2"; then
       : # no old version, nothing to do
     else