The FBI plotted to keep U.S. Magistrate Judge Sunil R. Harjani from taking the bench, Special Agent Brent Potter joked on Thursday.He said he and his colleagues were not happy when they learned last year that Harjani might be leaving the U.S. Attorney’s Office for the Northern District of Illinois for a position on the federal trial court.“Until his recent selection as a magistrate judge, Sunil was known as the …