[Merge] ~codyshepherd/livecd-rootfs/+git/livecd-rootfs:fix/riscv64-manifest-gen into livecd-rootfs:ubuntu/jammy

[Michael Hudson-Doyle]

Review: Approve

Seems like slightly strange factoring to have a function called install_grub be responsible for creating a manifest but you explanations make sense.
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https://code.launchpad.net/~codyshepherd/livecd-rootfs/+git/livecd-rootfs/+merge/475962
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