tests(processing): Update regression test targets to include dna width

[ns-rse]

Splits test_trace_image_disordered into two tests, the original compares dictionaries, the newer (suffixed with _dataframes) compares the dataframes/csv files that are produced, of which there are two and one needed updating to include the grain_width_mean column that #999 introduces.# TopoStats Pull Requests

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Before submitting a Pull Request please check the following.

• [x] Existing tests pass.
• [ ] Documentation has been updated and builds. Remember to update configuration.md, usage.md, and relevant processing sections under advanced.md. #1001
• [x] Pre-commit checks pass.
• [x] New functions/methods have typehints and docstrings.
• [ ] New functions/methods have tests which check the intended behaviour is correct. ~~Tests to be written in due course, this just gets the current changes passing the existing tests.

Optional

topostats/default_config.yaml

If adding options to topostats/default_config.yaml please ensure.

• [ ] There is a comment adjacent to the option explaining what it is and the valid values. N/A
• [ ] A check is made in topostats/validation.py to ensure entries are valid. N/A
• [ ] ~~Add the option to the relevant sub-parser in topostats/entry_point.py. …h and improved docstring~~ N/A