NEW HAVEN, Conn. — “We’re going to celebrate as a team. We’ll be together,” the Harvard senior and quarterback who became a starter this season, Chris Pizzotti, said before boarding a bus that would return his football team to Cambridge as Ivy League champions who ruined Yale’s undefeated season, beating them at the Yale Bowl 37-6. Their victory meal for the ride home consisted of beef, chicken, mashed potatoes, macaroni and cheese — all crammed into one plate — and orange Gatorade.