One of Keegan Murray’s first tests since the Kings drafted him fourth overall over the summer didn’t come on a basketball court. It came on a ping-pong table. “I’m not even good at ping-pong,” Murray said Monday at Kings’ media day, his unofficial introduction alongside other players before Tuesday’s start of training camp. “I just make the other players make the mistake.” Murray and his new Kings teammates put together an informal ping-pong tournament at an offseason gathering. The group had been working out at the team’s facility, playing pickup games, working out and getting to know one ano…