HONG KONG—Hong Kong’s government is facing growing pressure from business lobby groups to open borders or risk losing executives and investments as it shows no sign of easing one of the world’s strictest quarantine programs. Working on billion-dollar deals while locked in hotel rooms for three weeks is becoming common for bankers in Asia’s financial hub even as counterparts in places like London and New York go straight back to their offices after travel. Hong Kong’s decision in August to increase mandatory hotel quarantine to three weeks for arrivals from most countries has prompted a backlash from banks, hedge funds, and traders who say it is hampering new investment into the asset management market, and risks setting off a brain drain. Financial services contribute around 20 percent to Hong Kong’s gross domestic product, government statistics show. City leader Carrie Lam said on Tuesday many people had complained that quarantine policies …