Fedora IoT installer images have `inst.ks=hd:LABEL=Fedora-40-BaseOS-x86_64:/osbuild.ks`, boot to a hub complaining about incomplete kickstart

Current Fedora IoT installer images - built with osbuild - have an osbuild.ks file and a default kernel parameter inst.ks=hd:LABEL=Fedora-40-BaseOS-x86_64:/osbuild.ks that points to it. The file contains a single line:

ostreesetup --osname=fedora --url=file:///run/install/repo/ostree/repo --ref=fedora/rawhide/x86_64/iot --nogpg

...that's it. Obviously this is a very incomplete kickstart, so it causes anaconda to boot to interactive mode, with almost every spoke showing an attention flag caused by incomplete kickstart data:

this doesn't seem like it can be the intended experience. I don't know exactly when it started - it was between Fedora-IoT-ostree-x86_64-40-20231010.0.iso and Fedora-IoT-ostree-40.20231129.2-20231129.2.x86_64.iso , but I think the former was not built by osbuild, so it's not really a valid comparison. I don't think we've seen a 'successful' osbuild-built image yet, actually, so this may have been happening all along.

Filing here as it looks like the code responsible for adding the inst.ks param is in this repo.

Start by inspecting the image-builder code responsible for adding the inst.ks kernel parameter and the generated osbuild.ks file. Reproduce the issue with an affected Fedora IoT installer image and compare it with the earlier and later image versions mentioned. Done means the installer no longer enters interactive mode because of incomplete kickstart data.