Change `query_group_by` function to not accept `**kwargs`

[omad]

We could specify kwargs as type Any here, since it's not used. However, I think we should change the type of this method to only have the group_by argument. I think it was written this way for laziness, to not have to extract the group_by value in the calling function... not a good reason.

I think this counts as public API, so we should:

• fix the only 2 call sites to not use ** and just pass the group_by value.
• Raise a deprecation warning if kwargs is not None and remove it in the next major release.

Originally posted by @omad in https://github.com/opendatacube/datacube-core/pull/1788#discussion_r2057597965