Create drupal_nl config split

Acceptance Criteria

• A drupal_nl config split is created
• The split includes only la_nl-specific configurations.
• Shared configs stay in the default config set, not duplicated in the split.
• Clear separation between shared and project-specific configurations.
• Drush config-export and config-import work without errors for both sets.
• All changes are committed and pushed to the correct branch.
• A short note is added to the README or technical documentation explaining the split.