Updated tests/integration/test_vars_usage_in_yaml.py:
- Variables immediately followed by '(' are now treated as function calls,
not as set variables. This prevents false errors.
- Fixed detection of redirect_domain_mappings so it is no longer flagged
as unused.
See: https://chatgpt.com/share/68c3542d-f44c-800f-a483-b3e43739f315
