Delete unused ubuntu generator
Ubuntu generates a ubuntu.sources file since 24.04 release instead of sources.list. As far as people know the last use of apt-setup was as part of ubiquity, and as of 24.04, Ubuntu no longer ship ubiquity-based media.
I asked to Canonical employee (or ex-employee) and they agree (and one provides last sentence).
Edited by Stéphane Blondon