LOS ANGELES/NEW YORK (Reuters) – In the United States, it’s iced green tea. In South Korea, it’s fries.At least nine fast-food chains and restaurant companies surveyed by Reuters said some of their locations have been grappling with changing lists of brief shortages of key ingredients and products, as supply bottlenecks plague eateries.The list of hard-to-find items has included summertime staples such as wieners and chicken wings, and non-food items like plastic packing material and paper bags.On June 14 the web site of South Korea’s No. 1 fast-food chain, Lotteria, alerted customers that its eateries would substitute cheese sticks for its...