Cast of “The Barber of Seville,” Washington National Opera, 2009 (photo by Karin Cooper) Washington National Opera’s production of Rossini’s overexposed opera buffa The Barber of Seville was, on the surface at least, hardly an exciting way to open the Washington National Opera season. The second performance last night, however, proved that, in spite of the many deficits a company faces in making new something that is so familiar and even tired, it is…