By Elizabeth Piper, Andrew MacAskill and Alistair Smout BIRMINGHAM, England (Reuters) -British Prime Minister Liz Truss was forced on Monday into a humiliating U-turn after less than a month in power, reversing a cut to the highest rate of income tax that helped spark turmoil in financial markets and a rebellion in her party. Finance minister Kwasi Kwarteng said the decision had been taken with “humility and contrition”, after some lawmakers reacted with fury to suggestions that public and welfare spending could be cut to fund tax cuts for the richest. Elected by party members but not the broa…