message: Monitoring: Fix to show "-" character for empty severity labels
diff: @@ -374,7 +374,7 @@ const SilencedAlertsList = ({alerts}) => _.isEmpty(alerts)
  <Link className="co-resource-link" to={alertURL(a, a.rule.id)}>{a.labels.alertname}</Link>
  <div className="monitoring-description">{alertDescription(a)}</div>
  </div>
  - <div className="col-xs-3">{a.labels.severity}</div>
  + <div className="col-xs-3">{a.labels.severity || '-'}</div>
  <div className="dropdown-kebab-pf">
  <Kebab options={[viewAlertRule(a)]} />
  </div>
  @@ -472,7 +472,7 @@ const AlertRow = ({obj}) => {
  <AlertState state={state} />
  <AlertStateDescription alert={obj} />
  </div>
  - <div className="col-xs-2">{_.startCase(_.get(labels, 'severity', '-'))}</div>
  + <div className="col-xs-2">{_.startCase(_.get(labels, 'severity')) || '-'}</div>
  <div className="dropdown-kebab-pf">
  <Kebab options={state === AlertStates.Firing || state === AlertStates.Pending ? [silenceAlert(obj), viewAlertRule(obj)] : [viewAlertRule(obj)]} />
  </div>
  