DETROIT — Rock legend Carlos Santana collapsed during a performance Tuesday night at Pine Knob Music Theatre in Clarkston when he was overcome by the heat, his management team confirmed on Facebook early Wednesday. The 74-year-old musician was singing “Joy” before suddenly stopping, according to concertgoers who said the music stopped abruptly. “He was walking, playing and all of a sudden went down,” said Janet Brown of St. Clair Shores, who was attending her fourth Santana concert and celebrating a birthday. The lights dimmed, then venue officials announced Santana would not be returning to t…