Clean up legacy-helper.py as suggested #6270

Job	Run time
Cache identify	5s
Shellcheck	4s
Dependency	4s
Prepare	6s
Ruff check and force	11s
Check commit	22s
Run pytest using Python 3.13	15s
Run pytest using Python 3.14	23s
Run mypy	13s
Process test coverage	12s
Build and publish Python 🐍 distributions 📦 to TestPyPI	10s
Process test complexity	12s
	2m 17s

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