By Andrew MacAskill and Kylie MacLellan LONDON (Reuters) – Boris Johnson is stepping down as British prime minister, with several of his Conservative lawmakers now taking part in a leadership contest to replace him. There is no clear favourite and the candidates are not listed in order of likely prospects. Eight candidates were formally nominated in the leadership contest, with two of those knocked out in the first round of voting on Wednesday. The second round of voting will take place on Thursday. REMAINING IN THE CONTEST: KEMI BADENOCH Elected to parliament for the first time in 2017, Baden…