ATLANTA — From Cliff Levingston taking the final shot instead of Dominique Wilkins to the largest four-game blowout in NBA history, the Atlanta Hawks have plenty of playoff lowlights. Now, finally, there’s something to cheer about. For the first time, the Hawks are headed to the Eastern Conference finals, just one step away from playing for the first championship since the franchise moved from St. Louis to the Deep South in 1968.