One part of the Nets’ recent trip to China stood out in particular for Ziaire Williams. “The egg-tart custard that’s here, the specialty, that’s really good,” Williams said as their trip came to a close Sunday. “I’m a big foodie. McDonald’s here is a lot better.” But the trip carried much more weight than just unique foods and differences in fast-food chains. The Nets and Suns — who squared off in two preseason games at Venetian Arena in Macao — became the first NBA teams to play in China since