koji_hub: drop ssl.conf as it's no longer used
    
    koji hubs are now all behind proxies for tls termination, so they don't
    need to run https locally. This allows us to drop the koji self signed
    certs, at least the staging version of which had become too weak and was
    preventing httpd from starting on boot.
    
    Signed-off-by: Kevin Fenzi <kevin@scrye.com>