First try at fixing col setup without start stop. Model validator for…

[dulte]

… pydating is also removed

Change Summary

Changes how the colocation setup and colocator handles start and stop times

Related issue number

Fix #1211

Checklist

• Start with a draft-PR
• The PR title is a good summary of the changes
• PR is set to AeroTools and a tentative milestone
• Documentation reflects the changes where applicable
• Tests for the changes exist where applicable
• Tests pass locally
• Tests pass on CI
• At least 1 reviewer is selected
• Make PR ready to review

[lewisblake]

Can we not just leave this in?

[dulte]

We can. But then we have to remove the return self above. I'm not sure if this might lead to other strange behavior

[dulte]

Some test do not work due to

            if self.colocation_setup.stop is not None or not isinstance(
                self.colocation_setup.start, int
            ):
                raise ColocationSetupError(
                    "Conflict: only single year analyses are support for model "
                    'climatology fields, please specify "start" as integer '
                    'denoting the year, and set "stop"=None'
                )

part of the colocator code

[lewisblake]

@dulte pushing this back until September to match the milestone for the associated PR. This is the type of issue I think we should clarify at the AeroTools backend design retreat, so please keep in mind as an example.