Code review comment for ~waveform/ubiquity:prepare-package

Circling back to this; my understanding was the gnome-initial-setup was considered at some stage but rejected in favour of modifying the new installer to fit the pre-installed use-case. Obviously this didn't happen in noble, and we wound up sticking with oem-config there for the initial release.

I'm still not entirely clear on how those image builds even work because without this patch, the oem user *shouldn't* exist in the images for oem-config-prepare to run successfully (to be clear: the image *doesn't* build successfully in ubuntu-image locally without this patch). Probably something buried in livefs somewhere.