Ridership of Hong Kong’s embattled rail operator in July slipped back from a strong rebound in June as the third wave of Covid-19 infections drove the city’s economy further into stagnation.According to the MTR Corporation, patronage for domestic services was 91 million in July, down 34 per cent from 138 million a year ago. It also dropped 17 per cent compared with 110 million in June, which marked a rebound of 13 per cent from 97 million in May.Plagued by travel lockdowns around the world, the…