By Michelle Nichols and Maggie Michael UNITED NATIONS/CAIRO (Reuters) -Between 10,000 and 15,000 people were killed in one city in Sudan’s West Darfur region last year in ethnic violence by the paramilitary Rapid Support Forces (RSF) and allied Arab militia, according to a United Nations report seen by Reuters on Friday. In the report to the U.N. Security Council, independent U.N. sanctions monitors attributed the toll in El Geneina to intelligence sources and contrasted it with the U.N. estimate that about 12,000 people have been killed across Sudan since war erupted on April 15, 2023, betwee…