Fix ydb_slice (#3834)

Author: maximyurchuk

ydb/tools/ydbd_slice/__init__.py

@@ -497,7 +497,7 @@ def ssh_args():
     args.add_argument(
         "--ssh-user",
         metavar="SSH_USER",
-        default=[current_user],
+        default=current_user,
         help="user for ssh interaction with slice. Default value is $USER "
              "(which equals {user} now)".format(user=current_user),
     )

ydb/tools/ydbd_slice/nodes.py

@@ -128,7 +128,7 @@ def _copy_between_nodes(self, hub, hub_path, hosts, remote_path):
             if self._dry_run:
                 continue
             user = self._ssh_user or os.getenv("USER")
-            cmd = self._get_ssh_command_prefix
+            cmd = self._get_ssh_command_prefix(dst)
             cmd.extend([
                 "sudo", "rsync", "-avqW", "--del", "--no-o", "--no-g",
                 "--rsh='ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -l %s'" % user,