At an age many people retire – or expire – Judy Gethers who never worked a day in her life became a renowned gourmet chef. The granddaughter of a famed dairy restaurant owner on the Lower East Side, Ratner’s, she loved to eat well, but that was it. And then one day, sitting with her husband in Ma Maison, Wolfgang Puck’s upscale restaurant in Los Angeles, she suddenly decided she wanted to learn how to cook. She was 53. Puck put her to work as an unpaid intern in his kitchen: “You’ll be our slave