BEIJING — China will drop a travel tracing requirement as part of an uncertain exit from its strict “zero-COVID” policies that have elicited widespread dissatisfaction. At midnight on Monday, the smart phone app will cease to function, meaning residents’ travels will not be traced and recorded, potentially reducing the likelihood they will be forced into quarantine for visiting pandemic hot spots. China’s ruling Communist Party allows no independent parties to conduct verification and such apps have been used in past to suppress travel and free speech. It’s part of a package of apps that includes the health code, which has...