Maya Plisetskaya retired formally as a soloist when she was 63, but she never left ballet. On her 70th birthday, she debuted in “Ave Maya,” choreographed for her by Maurice Béjart. She danced “Ave Maya” again for her 80th anniversary and at 82 Plisetskaya, still steady on her high heels, once more danced Béjart’s piece at the Cap Roig Gardens festival in Spain.