Hong Kong’s monthly leases for ultra luxury residences have fallen by almost a third, as three successive months of street protests and the ongoing drought of high-paying financial jobs have deterred expatriate and mainland Chinese renters.Three-storey town houses of around 3,000 square feet (279 square metres) at the South District and on The Peak are now available for between HK$150,000 and HK$200,000 (US$25,000) per month, up to 30 per cent less than what they were going for three or four…