migrating old metadata (kdesrc-build action needed)

Ahoy

Currently we have two sets of duplicated metadata one in the ksb format and
one in yaml. Nico wants to only have one, and I for one agree with this.
There are also some broader repo-metadata changes coming, not sure how much
they impact kdesrc-build but the lack of input from the kdesrc-build side
is concerning at least. So, someone should get involved on those (see the
issues/MRs on repo-metadata for details).

As for the duplicated metadata it's my understanding kdesrc-build needs to
be updated to use these:
https://invent.kde.org/sysadmin/repo-metadata/-/tree/master/build-configs?ref_type=heads

Long story short: if nobody steps up and maintains kdesrc-build it will be
defunct in short order. But not all is lost! kde-builder acts as
replacement and is on top of the new metadata, so we are technically
already covered.

HS