The Hong Kong residential market has lost one of its most steady sources of tenants – mainland Chinese students – this summer, after most of the city’s universities moved to online teaching for the coming semester amid the coronavirus pandemic.Rents in some areas close to universities have dropped by about a third year on year. In Sha Tin, which usually caters to students of Chinese University, Baptist University and City University, mainland Chinese renters accounted for 20 per cent to 30 per…