The state School Building Authority has been making good on its threat to stop reimbursing Boston annually for a $40 million renovation of Hyde Park High School, six months after the city closed the building in violation of state funding rules. The decision was issued in a Dec. 19 letter to Superintendent Carol R. Johnson obtained by the Globe last week. In the letter, the authority said the remaining payments for the Hyde Park project, totaling $12.7 million, are currently on hold.’’