KATIE COURIC last night underwent her second on-air colonoscopy. Watching the procedure was not a horribly painful event. Nor was it an experience I would volunteer to repeat any time soon. For her very first night as CBS News diva, Katie spent a half-hour looking as if she desperately had to go potty. Her back was so stiff as she looked into the camera, pop-eyed and self-conscious, I feared it would snap. Her face was Botoxed beyond normal human endurance, proving that even pampered, overpaid news babes possess the courage to suffer for their art. And for the first time...