Alibaba Group Holding Ltd. plans to gradually wind down the last of its Costco-like members-only stores, underscoring its retreat from a hyper-competitive Chinese retail arena.Its supermarket chain Hema has begun shutting down premium “Hema X” outlets, which charge members an annual subscription for access, a person familiar with the matter said. China’s e-commerce leader is taking action to shore up overall profitability, the person said, asking to remain anonymous discussing a non-public decis...