By Siddharth Cavale and Arriana McLymore NEW YORK (Reuters) -Major U.S. retailers that recently scrambled to restock shelves amid product shortages disclosed this week that their stores are now packed with too much merchandise, and some are even doing what was unthinkable just a few months ago: discounting unsold goods. It’s a sign of possible more trouble to come for retailers amid soaring inflation and higher gas prices. With shoppers’ tastes quickly shifting, many retailers now find themselves with a surplus of merchandise, driving up costs. Costco Wholesale Corp said its inventories balloo…