Buildbot packages accessible in fixed repo URL per major version

It would be nice if the bb generated packages where available at fixed URLs

With this we could point users at latest version of packages as a testing version. So this would be like:

deb [trusted=yes] https://ci.mariadb.org/10.6/amd64-debian-10-deb-autobake/debs ./

and rpm like https://ci.mariadb.org/10.6/aarch64-centos-stream8-rpm-autobake/MariaDB.repo where the file contains a 10.6 reference rather than a tarbuildnum.

• same with Galera.
  https://ci.mariadb.org/galera/mariadb-4.x/