By Martin Quin Pollard and Ryan Woo BEIJING (Reuters) -Authorities in China’s capital warned on Tuesday that a COVID-19 surge in cases linked to a 24-hour bar was critical and the city of 22 million was in a “race against time” to get to grips with its most serious outbreak since the pandemic began. The flare-up means millions of people are facing mandatory testing and thousands are under targeted lockdowns, just days after the city started to lift widespread curbs that had run for more than a month to tackle a broader outbreak since late April. Authorities announced on the weekend a “ferociou…