Check if we have a pre-existing cutoff-based filter file from previous VQSR failure.

def _already_cutoff_filtered(in_file, filter_type):
    """Check if we have a pre-existing cutoff-based filter file from previous VQSR failure.
    """
    filter_file = "%s-filter%s.vcf.gz" % (utils.splitext_plus(in_file)[0], filter_type)
    return utils.file_exists(filter_file)