U.S. District Judge Ruben Castillo said Wednesday he plans to leave Chicago’s federal trial court at the end of September.Castillo said he is weighing various offers and has not yet decided where he will land after retiring from the bench.He may end up at a law firm, a mediation service or a law school, he said.He said there is a “slight possibility” he will remain on the bench. But he offered 90% odds that …