Migrate releng.py from systemd-releng
    
    Let's run the systemd-cd workflow from the systemd-releng repository
    (https://gitlab.com/CentOS/Hyperscale/releng/systemd-releng) in the
    gitlab rpm repository instead. The releng.py script was changed to
    expect to run from the rpm repository and doesn't clone the rpm
    repository from git.centos.org anymore.