[Merge] ~patviafore/livecd-rootfs/+git/livecd-rootfs:initramfs_less_boot_focal into livecd-rootfs:ubuntu/focal

[Pat Viafore]

Moving back to WIP because of https://bugs.launchpad.net/ubuntu/+source/livecd-rootfs/+bug/1902260, which indicates that how we change replace_kernel might mess things up a bit. Once that is resolved, there will probably be another backported change to this MP
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https://code.launchpad.net/~patviafore/livecd-rootfs/+git/livecd-rootfs/+merge/397376
Your team Ubuntu Core Development Team is requested to review the proposed merge of ~patviafore/livecd-rootfs/+git/livecd-rootfs:initramfs_less_boot_focal into livecd-rootfs:ubuntu/focal.