Reliance is making a bold bet on Shein, the ultra-fast-fashion giant that resumed operations in India earlier this year. And the Indian conglomerate needs the gamble to pay off.The pressure is mounting for India's largest retailer, whose retail arm posted a modest 9% EBITDA growth last year despite chairman Mukesh Ambani's public pledge to double profits within four years.The answer may lie in India's fast-fashion segment, which surged 30-40% in the year through March, according to consultancy f...