Rigify: cleanup PyCharm warnings in legacy face.

- Pep8 formatting: whitespace style issues, comments, long lines.
- Preserved formatting of a couple of tables through noqa tag.
- Renamed a few local variables for typos, clarity and scope conflicts.
- Commented out a duplicate key in the tweak_copyloc_L table.
- Added assertion in an impossible branch.

This should cause no functionality changes.