fix bug: complement data error (#6460)

dolphinscheduler-service/src/main/java/org/apache/dolphinscheduler/service/quartz/cron/CronUtils.java

@@ -185,6 +185,11 @@ public class CronUtils {
      */
     public static List<Date> getSelfFireDateList(final Date startTime, final Date endTime, final List<Schedule> schedules) {
         List<Date> result = new ArrayList<>();
+        if(startTime.equals(endTime)){
+            result.add(startTime);
+            return result;
+        }
+
         Date from = new Date(startTime.getTime() - Constants.SECOND_TIME_MILLIS);
         Date to = new Date(endTime.getTime() - Constants.SECOND_TIME_MILLIS);