By Andrew MacAskill and Elizabeth Piper LONDON (Reuters) -Voters in Britain will go to the polls in local government elections on Thursday where they are expected to punish Prime Minister Boris Johnson over a cost-of-living crisis and fines for breaking his own COVID-19 lockdown rules. The elections are seen as a test of support for Johnson, who became the first British leader in living memory to have broken the law while in office when he was fined last month for attending a birthday gathering in his office in 2020. A sharp rise in global energy prices that has pushed up consumers’ gas and el…