Make sure we dont have hidden options for backend and pipeline compiler (#2123)

move options based on **os.Getenv** into flags

---------
*Sponsored by Kithara Software GmbH*

pipeline/backend/kubernetes/service.go

@@ -1,3 +1,17 @@
+// Copyright 2022 Woodpecker Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package kubernetes
 
 import (