SPRINGFIELD — State public information laws require Chicago to preserve decades-old police misconduct records despite a provision in the police union’s collective bargaining agreement, the Illinois Supreme Court ruled Thursday.The 6-1 decision overturned an arbitrator’s decision that the city must destroy records after a certain period based on the 1981 union contract.Section 8.4 of that collective bargaining agreement provided that “all disciplinary investigation records” should be destroyed five years after their filing, …