BOSTON — A friend who had dinner with the Boston Marathon bombers hours after the attack is to be sentenced this week for misleading investigators.Khairullozhon Matanov was a friend of Tamerlan Tsarnaev and an acquaintance of Dzhokhar Tsarnaev. He pleaded guilty in March to misleading the FBI after the deadly 2013 bombings by deleting his computer files and failing to disclose contact he had with the brothers.