instance-mariadb.cfg.in:
  rename slowquerydex folder to slowquery_digest
mysql-querydigest.sh.in:
  exit 1 on error
  add date to the output file name of pt-query-digest to fit promise behavior
    https://lab.nexedi.com/nexedi/slapos.toolbox/blob/beb86eab2dee7178aa6e4795da0f56bb6cacaea1/slapos/promise/check_slow_queries_digest_result/__init__.py#L29
  review sh arguments handling
  end message: "ok" -> "Report generated successfully." or ..."failed with code $?"