Don't automatically add license header to code inside plugins dir. (#…

…66601)

Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>

.eslintrc.js

@@ -133,7 +133,7 @@ module.exports = {
      * Licence headers
      */
     {
-      files: ['**/*.{js,ts,tsx}'],
+      files: ['**/*.{js,ts,tsx}', '!plugins/**/*'],
       rules: {
         '@kbn/eslint/require-license-header': [
           'error',