API v3: remove last_build expandable field

[stsewd]

There is no data for this field in CF, so nobody is using it.

Closes https://github.com/readthedocs/readthedocs-corporate/issues/1874

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📚 Documentation previews 📚

• User's documentation (docs): https://docs--11730.org.readthedocs.build/en/11730/

• Developer's documentation (dev): https://dev--11730.org.readthedocs.build/en/11730/

[ericholscher]

I think we discussed removing all the expandable fields, unless we're using them? Woudl simplify the docs/code here, so might be worth doing.

cc @humitos

[humitos]

I'm fine removing expandable fields 👍🏼 . If we really need that data, we can always build regular API endpoint to return that data -- which has shown being a lot easier to maintain, in particular when related to permissions.

In the case of ?expand=active_version we already have ?active=true&built=true in the versions endpoint: https://readthedocs.org/api/v3/projects/test-builds/versions/?verbose_name=&privacy_level=&active=true&built=true&uploaded=&slug=&type=

We could add a new field in the _links if we want to have a direct URL to that filter.

[humitos]

Using the time machine: https://github.com/readthedocs/readthedocs-corporate/issues/1874#issuecomment-2333636295