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

[Pat Viafore]

The proposal to merge ~patviafore/livecd-rootfs/+git/livecd-rootfs:initramfs_less_boot_focal into livecd-rootfs:ubuntu/focal has been updated.

Commit message changed to:

Boot with an initramfs by default in cloud images,

When using a non-generic kernel, no change is made. Additionally, there is now a mechanism to detect initrdless boot fallback. When we attempt to boot with an initramfs and fail,
initrdless_boot_fallback_triggered is set to non-zero in the grubenv.
This value can be checked after boot by looking in /boot/grub/grubenv
or by using the grub-editenv list command.

Fixes double-boot issue in LP: #1870189

For more details, see:
https://code.launchpad.net/~patviafore/livecd-rootfs/+git/livecd-rootfs/+merge/397376
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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.