The Boston Bruins face one of their biggest tests of the season Saturday night, and they’ll have to do it without their starting goalie. Tuukka Rask is day to day with a lower body injury, and he didn’t travel with the B’s to New York for their showdown with the Islanders. That means backup Anton Khudobin will be in net as the Bruins try to keep pace with the Islanders for the final wild-card spot in the Eastern Conference. Both teams have 82 points, but New York officially passed Boston for the final playoff spot in the East thanks to its 4-3 shootout win over the Pittsburgh Penguins on Friday. The B’s now are