BEIJING, Oct 30 (Reuters) - Cities in central China hastily drew up plans to isolate migrant workers fleeing to their hometowns from a vast assembly facility of iPhone maker Foxconn (2317.TW) in COVID-hit Zhengzhou city, fearing the returnees may trigger coronavirus outbreaks. Zhengzhou, capital of Henan province, reported 167 locally transmitted COVID-19 cases in the seven days to Oct. 29, up from 97 infections in the prior seven-day period. Taiwan-based Foxconn, which has about 300,000 workers in Zhengzhou, has not disclosed the number of infected workers. Under China's ultra-strict zero-COVID policies, localities are mandated to act swiftly to quell any...