BERLIN (Reuters) - German Finance Minister Wolfgang Schaeuble declined to rule himself out as a candidate to replace Jean-Claude Juncker as chairman of euro zone finance ministers, in an interview published on Sunday. Juncker, Luxembourg's prime minister, said he would step down as Eurogroup chief at the end of this year or early next, leaving policymakers just four weeks to find a successor to fill a potential power vacuum. He has headed the group since 2005. ...