HOUSTON — Forrest Whitley’s wait is over. The Astros are promoting Whitley to the major-league roster, two sources told The Athletic on Tuesday, completing a circuitous journey for a man once regarded as baseball’s top pitching prospect. The Astros selected Whitley 17th overall in the 2016 draft, signed him for a $3.148 million bonus and once hailed him as their next homegrown ace. Injuries, ineffectiveness and a 50-game drug suspension before the 2018 season derailed the dream. Now, he will offer a fresh arm to a bullpen in desperate need of it. Because none of Houston’s other optionable relievers have…