dnfdaemon does not respect vendor pinning and repo priorities

[davide125]

Fedora Asahi Remix sets allow_vendor_change=False in dnf.conf and defines a number of repos with higher priority than the stock Fedora ones. I've noticed that dnfdragora doesn't seem to respect this, for example offering to update uboot-images-armv8 from 2023.07-6 (from https://copr.fedorainfracloud.org/coprs/g/asahi/u-boot) to 1:2023.07-3 (the upstream one from the fedora repo).

[Conan-Kudo]

This is a problem in dnfdaemon, so I've transferred the issue to the right place.