Remove empty config.h from default-ish keymaps (#15429)

keyboards/converter/siemens_tastatur/keymaps/default/config.h

@@ -1,19 +0,0 @@
-/*
-Copyright 2019 Yiancar
-
-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 2 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 <http://www.gnu.org/licenses/>.
-*/
-#pragma once
-
-// place overrides here