[llvm] [Workflow] Expand code-format-helper.py error reporting (PR #69686)

[Ryan Prichard via llvm-commits]

rprichard wrote:

The "[Workflow] make code-format-helper.py mypy-safe (NFC)" commit in this PR is actually part of https://github.com/llvm/llvm-project/pull/69691 instead.

https://github.com/llvm/llvm-project/pull/69686