desktop: remove references to subiquity snap

No subiquity snap is present on Desktop isos, these are cruft.

live-build/ubuntu/includes.chroot.minimal.standard.live/usr/bin/subiquity-shell

@@ -1,3 +0,0 @@
-#!/bin/sh
-exec sudo snap run subiquity
-

live-build/ubuntu/includes.chroot.minimal.standard.live/usr/lib/systemd/system/getty@.service.d/autologin.conf

@@ -1,3 +0,0 @@
-[Service]
-ExecStart=
-ExecStart=-/sbin/agetty --noclear -n --autologin ubuntu-server %I $TERM

live-build/ubuntu/includes.chroot.minimal.standard.live/usr/lib/systemd/system/serial-getty@.service.d/subiquity-serial.conf

@@ -1,9 +0,0 @@
-[Unit]
-Description=Subiquity, the installer for Ubuntu Server %I
-After=snapd.seeded.service
-StartLimitInterval=0
-
-[Service]
-Environment=SNAP_REEXEC=0
-ExecStart=
-ExecStart=/usr/bin/snap run subiquity.subiquity-service %I

live-build/ubuntu/includes.chroot.minimal.standard.live/usr/lib/systemd/system/serial-getty@sclp_line0.service.d/subiquity-serial.conf

@@ -1,4 +0,0 @@
-[Service]
-StandardOutput=tty
-ExecStart=
-ExecStart=/usr/bin/snap run subiquity --ssh

live-build/ubuntu/includes.chroot.minimal.standard.live/usr/lib/systemd/system/snap.subiquity.subiquity-service.service.d/subiquity.conf

@@ -1,14 +0,0 @@
-[Unit]
-IgnoreOnIsolate=yes
-After=systemd-user-sessions.service plymouth-quit-wait.service snap.seeded.service
-
-[Service]
-Environment=SNAP_REEXEC=0
-UtmpIdentifier=tty1
-TTYPath=/dev/tty1
-TTYReset=yes
-TTYVHangup=yes
-TTYVTDisallocate=yes
-KillMode=process
-IgnoreSIGPIPE=no
-SendSIGHUP=yes