By Elizabeth Piper and Andrew MacAskill LONDON (Reuters) -Former finance minister Rishi Sunak and foreign secretary Liz Truss made the final two candidates on Wednesday to become Britain’s next prime minister, kickstarting the last stage of the contest to replace Boris Johnson. Sunak has led in all rounds of the voting among Conservative lawmakers, but it is Truss, who seems to have gained the advantage so far among the around 200,000 members of the governing party who will ultimately choose the winner. The final stretch of a weeks-long contest will pit Sunak, a former Goldman Sachs banker who…