By Alistair Smout LONDON (Reuters) -British Prime Minister Liz Truss said allies should stand firm on Ukraine and ignore Russian President Vladimir Putin’s “sabre-rattling”. Truss, who met U.S. President Joe Biden and France’s Emmanuel Macron on her first foreign trip as prime minister to New York last week, in an interview with CNN called on like-minded democracies to be firm against “autocratic regimes”. Putin last week ordered a partial mobilisation of troops and raised the possibility of nuclear conflict. Truss said Putin was escalating his invasion of Ukraine because he wasn’t winning and…