An arbitrator’s finding that newly promoted Cook County Forest Preserve District police sergeants are entitled to a larger salary increase was rejected by a state appeals panel Tuesday.The 1st District Appellate Court found that arbitrator James R. Cox’s findings on salary increases were not rooted in the contract between the district and the Illinois Fraternal Order of Police Labor Council, the sergeants’ union.The collective bargaining agreement between the union and the district does not spell out how …