The chicken used to make Food Festival store-brand chicken soups for the past three years has been reported missing from the United Canning Co. plant in Sharpsburg. Police say that the chicken will probably be disoriented and surly, and is likely to smell rather ripe, not having had a bath in three days. Anyone with information on the whereabouts of the chicken is requested to contact the United Canning Co. directly or through the customer-service counter at any Food Festival supermarket. A reward of 29¢, in the form of discount coupons for store-brand soup, is offered for information leading to the successful recapture of the chicken.