Ahead of a reimagined Nathan’s Fourth of July Hot Dog Eating Contest, a team of elite eaters gathered on a Williamsburg rooftop on Friday to weigh in for a pandemic edition of the annual food-fest. The spectacle — held for decades at the corner of Stillwell and Surf avenues in Coney Island — typically boasts a rambunctious crowd of thousands. Officials announced in mid-June that the 2020 frankfurter frenzy would go on as planned — but on a much smaller scale, taking place without a crowd in…