QORQANYA, Syria — U.S. military officials are walking back claims that a recent strike in Syria killed an influential al-Qaeda figure, following assertions by the dead man’s family that he had no ties to terrorists but was a father of 10 tending to his sheep when he was slain by an American missile.Lotfi Hassan Misto, 56, whose family identified him as the victim of a Hellfire missile attack on May 3, was a former bricklayer who lived quietly in this town in northwest Syria, according to interviews with his brother, son and six others who knew him. They described a...