Donning a thin black headband that matched the Mavericks’ City Edition jerseys, Luka Doncic looked like he’d either come to American Airlines Center for a Duran Duran concert or an ‘80s aerobics class. He did not, however, appear to sweat all that much while bewildering the undermanned Utah Jazz with a 29-point triple-double ... in the first half alone. By the time he exited for good, after the…