[Merge] ~juliank/grub/+git/ubuntu:resilient-boot into ~ubuntu-core-dev/grub/+git/ubuntu:ubuntu

[Julian Andres Klode]

@raharper could use some review of the debconf keys. The logic for installers is to continue to mount one ESP to /boot/efi, and add all other disks using their /dev/disk/by-id/ alias to the grub2/efi_install_devices key.
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https://code.launchpad.net/~juliank/grub/+git/ubuntu/+merge/381462
Your team Ubuntu Core Development Team is requested to review the proposed merge of ~juliank/grub/+git/ubuntu:resilient-boot into ~ubuntu-core-dev/grub/+git/ubuntu:ubuntu.