China’s top leadership launched an expansive sweep of the nation’s agricultural, industrial and tech hubs this week, gathering “frontline” data ahead of a crucial GDP release in mid-July and a high-stakes Politburo meeting at the month’s end.On Wednesday, President Xi Jinping conducted a field trip to Dezhou, an agrarian city in the northern Shandong province, where he visited cornfields and a village. During the tour, he highlighted the need to enhance production and yield to guarantee food...