Fix license header linter config

tools/.golangci.yaml

@@ -5,9 +5,6 @@ issues:
   max-same-issues: 0
   exclude-files:
     - ^zz_generated.*
-    - test/
-    - pkg/leaselocker/
-    - internal/controller/suite_test.go
 linters:
   disable-all: true
   enable:
@@ -87,4 +84,20 @@ linters-settings:
         disabled: false
   # https://golangci-lint.run/usage/linters/#goheader
   goheader:
-    template-path: ./tools/license_header.txt
+    values:
+      regexp:
+        AUTHOR: ^Copyright 2024 (The Kubernetes authors|Swisscom \(Schweiz\) AG)\.
+    template: |-
+      {{ AUTHOR }}
+
+      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.