By Andrew Chung and Lawrence Hurley WASHINGTON (Reuters) -The U.S. Supreme Court on Monday allowed North Carolina and Pennsylvania to use electoral maps approved by state courts to replace ones deemed to have given Republicans unfair advantages, improving Democratic chances of retaining control of the U.S. House of Representatives in November. The justices denied Republican requests to put on hold lower court rulings that adopted court-drawn boundaries for North Carolina’s 14 House districts and Pennsylvania’s 17 House districts to replace electoral maps devised by Republican-controlled legisl…