Kroger Co. — parent of Colorado's King Soopers and City Market supermarket chains — could be a prime bidder for some Rite Aid or Walgreens drug stores that will need to be sold when those two companies finally complete their merger later this year. Cincinnati-based Kroger (NYSE: KR), the nation’s largest operator of traditional supermarkets, is a potential buyer of some of the 500 stores that will likely be put up for sale, according to a Bloomberg report. Kroger was rumored to be a potential…