Under-used comedic powerhouse Leslie Mann had heretofore been eclipsed by her comedy-dynasty-ruling husband, Judd Apatow. Then along came 2014’s “The Other Woman.” While this mediocre farce about cheating husbands is not overly special, Leslie Mann certainly was. Talk about underrated; with “The Other Woman,” Leslie Mann had arrived. Also, a new comic duo was born. Teaming up…