Change the schedule of Elasticsearch cronjobs

Issue

• How to change the schedule of Elasticsearch cronjobs?
• Cronjobs run every 15 min, How can one change it to run every 30 min?

# oc get cj -n openshift-logging
NAME                           SCHEDULE       SUSPEND   ACTIVE   LAST SCHEDULE   AGE
curator                        30 3 * * *     False     0        7h59m           50d
elasticsearch-delete-app       */15 * * * *   False     0        14m             50d
elasticsearch-delete-audit     */15 * * * *   False     0        14m             50d
elasticsearch-delete-infra     */15 * * * *   False     0        14m             50d