Switch to native format to work with the GitLab-to-OBS pipeline

We wish to use only the Apertis CI pipeline workflow to build source
packages from Apertis GitLab and then submit them to OBS.

For packages where Apertis is the upstream the simplest approach is to
set them up as native packages to avoid having to generate orig tarballs
and manage changes on top of them.`

Signed-off-by: Andrew Lee (李健秋) <andrew.lee@collabora.co.uk>