By Philip Pullella VATICAN CITY (Reuters) -Pope Francis attended but did not preside at an Easter vigil service in St. Peter’s Basilica on Saturday night, presumably because of recurring leg pain that has forced him to curtail some activities. Italian Cardinal Giovanni Battista Re replaced the pope as the main celebrant at the service, which involved a procession in near-total darkness up the central nave of Christendom’s largest church. The pope sat at the front of the basilica in a large white chair on the side and appeared to be alert. The Vatican said he would read the homily later in the …