Fix land fraction ancil creation function

[maxwhitemet]

Addresses https://github.com/metoppv/mo-blue-team/issues/1204

1. Fixes a misreading/typo regarding the delineation between land and 'water bodies': 'water bodies' start at classification code 40, not 39. This is demonstrated in table 1, table 2 and table 3. I imagine this was caused by these tables being difficult to find, and so that manual counting was used from page 67 of the official manual.

2. Fixes an accidental line break in a docstring and ensures the resulting cube has an appropriate name.

Testing:

• Ran tests and they passed OK

[mo-jbeaver]

I added a few small comments but overall happy with the changes.
The unit tests all ran as expected. However, the unit test should be updated to include the new variable added to the generate_roughness_length_at_sites function, checking that the pytest still runs as expected when ignore_grid_match = False and True.
Additionally, there probably should be an acceptance test that goes with these functions.

[maxwhitemet]

Thanks @mo-jbeaver. I have addressed all feedback

[Copilot]

Pull request overview

This PR updates miscellaneous ancillary-generation helpers to (a) support optionally bypassing strict grid-hash matching during spot extraction and (b) ensure the land area fraction output cube has a consistent, explicit name, alongside a small docstring formatting fix.

Changes:

• Add an ignore_grid_match passthrough option to generate_roughness_length_at_sites, forwarding to SpotExtraction.
• Fix a docstring line break and explicitly rename the concatenated land area fraction cube to "land_area_fraction".
• Expand unit tests to cover roughness-length ancillary generation with ignore_grid_match both enabled and disabled.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
improver/generate_ancillaries/generate_miscellaneous_ancillaries.py	Adds ignore_grid_match support for spot extraction and ensures land area fraction output cube is explicitly named; docstring formatting cleanup.
improver_tests/generate_ancillaries/test_miscellaneous_ancillaries.py	Parametrizes roughness-length ancillary test to exercise ignore_grid_match True/False.

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[mo-jbeaver]

Happy with all the changes made and the tests ran successfully.