fix and simplify Dpkg::Vendor::PureOS as minimal subclass
Dpkg::Vendor::PureOS was created as a copy of Dpkg::Vendor::Debian, borrowing parts of Dpkg::Vendor::Ubuntu, and adding some unique bits.
- borrowed code contains bogus/needless references to Ubuntu
- borrowed code contains no-op calls to SUPER (because it was borrowed from a subclass)
- code is hard to maintain going forward
This patch refactors Dpkg::Vendor::PureOS as a subclass of Dpkg::Vendor::Debian (similar to Dpkg::Vendor::Ubuntu), fixes a warming to reference PureOS (not Ubuntu), drops unneeded Ubuntu-specific parts, and only minimally overloads run_parts().
Edited by Jonas Smedegaard