After a chastening crackdown that wiped billions off their value and forced top executives out of the public eye, China’s technology giants are back in favor and on the front foot, making deals and snapping up assets. At the top of the pile are Alibaba Group Holding Ltd. and Tencent Holdings Ltd., two huge players that used to compete for acquisitions in everything from ride hailing and video streaming to online finance, until their wings were clipped by Chinese authorities concerned about their...