Just a week after NBC cleaned house at “Heroes,” it’s doing the same now with “Knight Rider.” Gone are Sydney Tamiia Poitier, Yancey Arias and Bruce Davison, and here is what showrunner Gary Scott Thompson called a “reboot.” “We’re moving away from the terrorist-of-the-week formula and closer to the original, making it a show about a man and his car going out and helping more regular people.” Poitier and Davison were a part of the original “Knight Rider” backdoor pilot that aired last spring, playing Carrie Rivai and Charles Graiman. Arias was added when the actual series started, playing Alex Torres. All three will remain through the first 13 episodes, but will not be a part of “Knight Rider’s” planned mid-season retooling, a change that apparently had been in the works since …