GLENDALE, Ariz. — It was workmanlike. Maybe at times not all that exciting. And, for an instant, even a little anxiety-inducing. But when it was over, the Seahawks had one of the most satisfying wins they’ve had in years here Sunday, a 31-21 victory over the Arizona Cardinals that gave them a sweep over one of their most heated NFC West rivals. It was also the Seahawks’ fourth straight win, improving their record to 6-3 and keeping them in front of the NFC West by a game-and-a-half. And it was achieved with another stellar performance by a Seattle defense that a month ago was drawing compariso…