An old tradition is getting a redesign at Boston Ballet, which this week premieres artistic director Mikko Nissinen's reenvisioned production of Tchaikovsky's "The Nutcracker." Some of the choreography is new, and so are some of the characters, but the most sweeping change is in the look of the piece, which debuts fresh sets and costumes — almost 350 of them — by Robert Perdziola. "The Nutcracker" runs Nov. 23-Dec. 30 at the Boston Opera House.