Comment 1 for bug 1831631

Pros:
 - installing them in the squashfs is faster than installing them at build time
 - if we believe they should always be installed, it simplifies the installer logic
   - except that we're also converging on a single installer code base, so it doesn't simplify things too much to have it in livecd-rootfs instead of in curtin (and curtin still has to trigger grub-install to the target disks, either by replaying the package postinsts on the target or by manually calling grub-install)

Cons:
 - this moves us farther away from being able to converge the server squashfs as used by subiquity with the lxd squashfs published by cloud images. (we don't currently have a path forward for how to build this once and consume it in both places, but nevertheless I don't like that we currently build it twice.)