[Merge] ~seb128/livecd-rootfs:canary-image-tweaks into livecd-rootfs:ubuntu/master

[Sebastien Bacher]

On installer vs new-installer, it feels like the delta is small enough that the current special casing should be enough, especially that we do plan for the new installer to be the desktop one at some point and not maintain the canary variant
-- 
https://code.launchpad.net/~seb128/livecd-rootfs/+git/livecd-rootfs/+merge/405807
Your team Ubuntu Core Development Team is requested to review the proposed merge of ~seb128/livecd-rootfs:canary-image-tweaks into livecd-rootfs:ubuntu/master.