radosgw-admin: adapt task to recent changes
radosgw-admin: adapt task to recent changes

Signed-off-by: Yehuda Sadeh <48638f9c2a62c4fd20be28d0bdad68f5cd041402@inktank.com>

t-miyamae/teuthology,robbat2/teuthology,zhouyuan/teuthology,michaelsevilla/teuthology,t-miyamae/teuthology,tchaikov/teuthology,SUSE/teuthology,dmick/teuthology,caibo2014/teuthology,dreamhost/teuthology,ivotron/teuthology,ceph/teuthology,yghannam/teuthology,ceph/teuthology,tchaikov/teuthology,SUSE/teuthology,SUSE/teuthology,ivotron/teuthology,yghannam/teuthology,dreamhost/teuthology,caibo2014/teuthology,dmick/teuthology,dmick/teuthology,ktdreyer/teuthology,ktdreyer/teuthology,michaelsevilla/teuthology,robbat2/teuthology,zhouyuan/teuthology