Update config for twoweek compose
    
     * It is not a layered product (otherwise base_product would need to be
       configured).
     * Add Cloud variant. Its repos are used in image_build section.
     * Add source repositories. They are needed for depsolving.
     * Remove release_id_allow_missing, which should be product_id_ and only
       makes sense if product_id is configured.
     * Remove notification_script, as this is handled by CLI option
     * Remove link_files: it's called link_type and hardlink-or-copy is
       default.
     * Set bootable to False, we don't need buildinstall here.
     * Use repos and install trees from regular F24 compose for building
       images
     * Skip some phases to make it faster: we don't need to gather any
       packages, so we can skip pkgset, gather and extra_files phases.
    
    Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>