LONDON (Reuters) -British Prime Minister Boris Johnson will block an attempt by the opposition Labour Party to call a confidence vote in his government on Wednesday, a Labour spokeswoman said on Tuesday. Labour said earlier it intended to call such a vote to try to prevent Johnson remaining in power whilst his successor is chosen – a process which is expected to take up until Sept. 5. [nS8N2Y1069] By convention the government, which controls the allocation of parliamentary business, would normally free up time for a confidence vote called by the main opposition party. “This clapped-out governm…