Node template isn't licensed, remove left-over GPL header (#12937)

substrate/bin/node-template/node/src/benchmarking.rs

-// This file is part of Substrate.
-
-// Copyright (C) 2022 Parity Technologies (UK) Ltd.
-// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
-
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// GNU General Public License for more details.
-
-// You should have received a copy of the GNU General Public License
-// along with this program. If not, see <https://www.gnu.org/licenses/>.
-
 //! Setup code for [`super::command`] which would otherwise bloat that module.
 //!
 //! Should only be used for benchmarking as it may break in other contexts.