[Py Reformat] Exclude third-party in code-format-helper.py (llvm#…

…83872)

Follow-up from PR llvm#83491. `Darker`'s configuration is ignored because of the way we invoke it - with an explicit list of files. We need to filter it in `code-format-helper.py`.

llvm/utils/git/code-format-helper.py

@@ -125,6 +125,7 @@ def update_pr(self, comment_text: str, args: FormatArgs, create_new: bool) -> No
  pr.as_issue().create_comment(comment_text)
 
  def run(self, changed_files: List[str], args: FormatArgs) -> bool:
+ changed_files = [arg for arg in changed_files if "third-party" not in arg]
  diff = self.format_run(changed_files, args)
  should_update_gh = args.token is not None and args.repo is not None