By now, many high school seniors have learned whether they were admitted to the Ivy League of their choice. But will they find grimy dorms and bad food when they get there? Harvard has scaled back its cleaning staff and frozen some faculty salaries, while Yale and Brown have halted construction projects. Even the 24-hour Princeton University store will now close between 3 and 8 a.m. Lucky students planning to attend Columbia can get a little closer to their classmates in more crowded lecture halls. And Dartmouth freshmen are going to have to look farther for dinner as the University plans on closing a cafeteria and cutting back its dining staff.