The formation, creation, or continued existence of library boards shall not be considered or construed in any manner as mandatory upon (i) any city or town with a manager; (ii) any county with a county manager, county executive, urban county manager, or urban county executive form of government; (iii) any county that has adopted a charter; or (iv) the Counties of Botetourt, Caroline, Chesterfield, King and Queen, and Shenandoah, by virtue of this chapter.