"A federal judge has awarded more than $2 million to a man wrongly convicted based on evidence falsified by Annie Dookhan, the former state chemist who created a multimillion-dollar crisis in the state’s criminal justice system. It is the first case in which Dookhan has been ordered to compensate any of the thousands of defendants whose cases she tainted. U.S. District Judge Indira Talwani determined that Leonardo Johnson, 53, of Dorchester, is entitled to compensatory and punitive damages for the 15 months he served in prison, because Dookhan gave “false testimony to convict an innocent man.’’