message: Monitoring: Show '-' when alerting rule has no duration
diff: @@ -571,7 +571,7 @@ const AlertRulesDetailsPage = withFallback(
  {_.isInteger(duration) && (
  <>
  <dt>For</dt>
  - <dd>{formatPrometheusDuration(duration * 1000)}</dd>
  + <dd>{duration === 0 ? '-' : formatPrometheusDuration(duration * 1000)}</dd>
  </>
  )}
  <dt>Expression</dt>
  