By William Schomberg and Paul Sandle LONDON (Reuters) – Britain’s new Prime Minister Rishi Sunak earned cheers from his lawmakers and plaudits from political commentators on Wednesday as he locked horns with the opposition Labour Party in parliament for the first time since becoming leader. Sunak, seeking to end a period of political instability that has seen two previous prime ministers leave Downing Street in two months, struck a confident tone as he sought to get his Conservative Party off the back foot. The 42-year-old – who became the youngest prime minister in modern British history when…