PORTLAND, Maine — Though it began with a family pizza recipe, Bill’s Pizza owner John Bradbury knew there were non-culinary factors keeping him in business too. “The pizza was there, but it was kind of an excuse for people who were trying to secure the deal with” — he checks his phrasing — “whoever they were trying to chat with for the rest of the night,” Bradbury said. For decades, Bill’s Pizza was the city’s default afterhours meetup spot, the safety net for people hitting it hard in the city’s illustrious Old Port strip of bars, pool halls and dance clubs. But Bradbury doesn’t witness those kinds of scenes anymore.