Diplomats in town for the UN General Assembly are meeting world leaders by day and high-end hookers by night, sources tell Page Six. And to meet demand for the illicit accords, high-priced escorts allegedly gather in the Big Apple from as far away as Las Vegas and Europe. “Business goes up 20% to 25%,” said one demimonde source familiar with the sex summits. “Girls literally fly in from Vegas and Europe . . . it’s like a hooker convention." The insider added of the erotic aides and their international clients, “They go to hotels because they can’t go to the...