Alibaba Group Holding Ltd.’s shares surged to their highest in nearly four years after revealing plans to ramp up AI spending past an original $50 billion-plus target, joining tech leaders pledging ever-greater sums toward a global race for technological breakthroughs.Chief Executive Officer Eddie Wu anticipates overall investment in artificial intelligence accelerating to some $4 trillion worldwide over the next five years — and Alibaba needs to keep up. The company will soon add to a plan laid...