Rework safety guard to support empty EFI component

[travier]

In the automotive use case, some images will have empty EFI components so we should support that.

In #994, we added a check that makes sure the EFI component has at least 2 entries, which thus fails.

What we want instead if the following:

• If there are no EFI component found, then we don't include EFI.json
• If there are some EFI component found:
  • Check if shim is part of them:
    • If it is, then there must be another component (i.e. bootloader) included
    • If it's not, do nothing special
  • Check if grub is part of them:
    • If it is, then there must be shim as another component
    • If it's not, do nothing special

[alexlarsson]

Also, if these fail, please print actual errors, not assertions.

[travier]

From a side discussion, it's not great that are hardcoding in the code what components should be in the image as this will likely vary in the future and does vary today for aarch64 & risc-v. So maybe we should just remove this check completely.

[travier]

OK let's revert that change and add the checks per-architecture in https://gitlab.com/fedora/bootc/base-images/-/blob/main/minimal/bootupd.yaml?ref_type=heads#L36 instead

[travier]

Moving the check on the image building side would look like: https://pagure.io/workstation-ostree-config/pull-request/718. Maybe we should add command line arguments to generate-metadata to tell bootupd to fail if something is missing:

/usr/bin/bootupctl backend generate-update-metadata --expect grub2 --expect shim

[cgwalters]

/usr/bin/bootupctl backend generate-update-metadata --expect grub2 --expect shim

SGTM