Opening Night features a new Aida, conducted by Yannick Nézet-Séguin and starring Anna Netrebko, Anita Rachvelishvili, and Piotr Beczała, in a new staging by Michael Mayer.Maestro Nézet-Séguin, in his third season as Music Director, will conduct six operas, including new stagings of Aida, Don Giovanni, and Dead Man Walking, as well as three classic revivals and two Met Orchestra concerts at…