fix: No longer install LXD snap in unminimize script (LP: #2066905)
The LXD snap is no longer seeded in any images since Noble+ so the LXD related unminimize logic in
./live-build/auto/build?h=ubuntu/noble and ./live-build/ubuntu-server/hooks/01-unminimize.chroot_early
is no longer required.
lxd-installer can remain installed.
MP: https://code.launchpad.net/~philroche/livecd-rootfs/+git/livecd-rootfs/+merge/466316