GENEVA/BRUSSELS (Reuters) - World Trade Organization head Roberto Azevedo will step down a year earlier than planned in August, he said on Thursday, in a surprise move as the trade body struggles to rein in global tensions and coordinate responses to the COVID-19 pandemic.The 62-year-old Brazilian has been director-general since 2013 and is serving a second term that was due to conclude at the end of August 2021.Azevedo said that he had taken a "personal decision" after talking with his family..