Any school board of a Class IV or Class V school district or certificated employee thereof may require that hearings held pursuant to sections 79-824 to 79-839 and such other hearings as designated by the school board be conducted by a hearing officer as specified in sections 79-841 and 79-842. If a hearing is held before such a hearing officer, the requirements of section 79-831 that final action must be taken by the school board on or before May 15 of each year and that a hearing must be held within thirty days of the date of the request for a hearing shall not apply.