By Siddharth Cavale and Arriana McLymore BENTONVILLE, Ark. (Reuters) -Walmart Inc shareholders on Wednesday struck down by an overwhelming margin an activist investor-led proposal asking the retailer to produce a report assessing the impact on its employees if the U.S. Supreme Court rolls back abortion rights. The proposal, made by Clean Yield Asset management on behalf of activist investor Julie Kalish, urged Walmart’s board to detail “any known and any potential risks and costs to the company caused by enacted or proposed state policies severely restricting reproductive rights” by the end of…