fix(clang-tidy): apply ignore patterns when `target-files` is provided

[xmfcx]

Summary

The clang-tidy action applies .clang-tidy-ignore and */test/* exclusion only in the find fallback path. When target-files is provided directly (e.g. by diff-based workflows), those filters are entirely bypassed.

This means callers that provide target-files must duplicate the filtering logic at the workflow level.

Expected behavior

Ignore patterns should be applied regardless of whether target-files is provided or files are discovered via find.

References

• fix(workflows): exclude all test folders in the build-and-test-diff-reusable.yaml autoware_core#1026 (review comment)
• ci(clang-tidy): exclude test files from clang-tidy-ignore autoware_core#1027 (comment)