Move per-flavor update test variables from here to the templates
    
    We're setting per-flavor update test variables here for no
    obvious reason, when the usual procedure would be to do it in the
    templates. The HDD variables do need + prefixes when set in the
    templates, but that isn't really a problem. This helps with
    https://progress.opensuse.org/issues/119200 by shortening the
    request URI length.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>