By Dhara Ranasinghe and Sujata Rao LONDON (Reuters) – Worried about record-high inflation, the European Central Bank may have significantly raised the threshold where it might staunch bond market sell-offs in Italy and other weaker euro bloc countries. Markets across poorer, debt-laden southern Europe reacted with shock to the ECB’s move to walk back earlier pledges not to raise rates this year. They recoiled too at the signal that its bond-buying scheme — a lifeline for southern Europe — could be unwound sooner and faster than expected. The hawkish pivot sharply lifted yields on ten-year bo…