remove admin_token_auth from the [pipeline:public_api],
        [pipeline:admin_api], and [pipeline:api_v3] sections

def _update_keystone_paste_ini(self):
        """remove admin_token_auth from the [pipeline:public_api],
        [pipeline:admin_api], and [pipeline:api_v3] sections"""
        with open('tmp_keystone_paste_ini_' + env.host_string, 'w') as f:
            f.write(conf_keystone_paste_ini)
        files.upload_template(filename='tmp_keystone_paste_ini_' + env.host_string,
                              destination='/etc/keystone/keystone-paste.ini',
                              use_sudo=True,
                              backup=True)
        os.remove('tmp_keystone_paste_ini_' + env.host_string)