BAGHDAD — Iraqi forces battled Islamic State fighters for a third day in a remote western town far from Mosul on Tuesday, but the U.S.-led coalition insisted the latest in a series of “spoiler attacks” had not forced it to divert resources from the fight to retake Iraq’s second-largest city. Iraqi Prime Minister Haider al-Abadi acknowledged that the militants briefly seized the local government headquarters in the western town of Rutba, offering new details about the assault, which U.S.