(Recasts with comments by Bank of Canada governor) OTTAWA, May 20 (Reuters) - The Bank of Canada said on Thursday that Canada’s hot housing market and high household debt levels had left the economy more vulnerable to economic shocks, but made clear it would not raise interest rates to cool the frenzy. A housing market boom and linked rise in mortgage lending has helped buoy economic growth in the short-term, but they increase the risk over the medium-term, the central bank said in its annual review of financial systems. Despite the intensifying risks, the focus remains on getting the harde...