[FIX] packaging: create rpm repo from container

The createrepo Debian package is not available in Ubuntu anymore, this
can cause problems on Ubuntu based build systems.

In order to solve that once and for all, with this commit the rpm repo is
generated from a Docker container.

Fixes #63419

closes odoo/odoo#63570

Signed-off-by: Christophe Monniez (moc) <moc@odoo.com>