There was a big demand for the recent issue of the New York Law Journal because it contained a list of the names and addresses of the 5,000-plus people who just passed the state bar exam. But those hoping to get the address of John F. Kennedy Jr. were disappointed because the Journal had honored his request to withhold his address for the sake of privacy. Kennedy, a member of the Manhattan district attorney's staff, recently passed the bar after failing on his first two tries.