By Greg Bishop As the left tackle prepares for the Super Bowl—against his former team—a look back on his fateful decision to join a wunderkind first-year coach in L.A. For years, Andrew Whitworth told Bengals teammates he would retire. He insisted, every fall, starting around 2011. This is the year, he’d say, I think this is the last one, before inevitably returning for another season—and another season after that, and another season after that. He’s 40 now, the second-oldest nonspecialist in the NFL this season, after that Brady fellow. He’s older, wiser and grayer. He’s closer (maybe, must b…