TOKYO, April 13 (Reuters) – Japanese technology investor SoftBank Group Corp (9984.T) has moved to sell almost all of its remaining shares in Alibaba Group Holding Ltd (9988.HK), , the Financial Times reported, sending the Chinese e-commerce major's stock tumbling. The sale would come as valuations of China's big tech firms have started recovering this year after an end to two years of heightened regulatory scrutiny, providing a window for long-time investors such as SoftBank to reduce exposure to an economy battered by strict pandemic policies and Sino-U.S. tension. SoftBank's share price was little changed on Thursday, tracking the broader…