LONDON — The cost of long-term borrowing for the British government is at its highest in nearly 30 years, as the country's influential bond market braces itself for an election that could determine the fate of Prime Minister Keir Starmer. Voters will elect more than 4,800 local council representatives on Thursday, which is expected to cost the ruling Labour party as many as 2,000 seats — and deal a blow to Starmer's already shaky leadership . Votes are expected to shift in favor of right-wing