SHANGHAI (Reuters) – More than 20,000 bankers, traders and other workers are bedding down in office towers in Shanghai’s Lujiazui district as they bid to keep China’s giant financial hub ticking over through a COVID-19 lockdown, according to local administration officials. Brokerages, asset managers and financial exchanges in Lujiazui – China’s answer to Wall Street – rushed to summon key personnel to offices ahead of Monday’s lockdown in Shanghai, and prepared sleeping bags and basic supplies for overnight stays. Some have also adopted two-team rotation shifts, and initiated disaster recovery…