Uber has shuttered its self-driving testing program in Arizona and laid off close to 300 workers there — most of them test drivers, or “vehicle operators” — two months after one of its autonomous cars killed a pedestrian, the company said on Wednesday. The company had been testing its self-driving technology in the state since 2016, but halted operations in the wake of the March crash. The company’s testing was also indefinitely suspended by the Arizona governor’s office....