refactor: move groups to persons db

[pl]

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Problem

We're breaking out the persons DB and decided to move groups along with it.

Changes

Changes all queries to postgres_group and postgres_grouptypemapping to use either PERSONS_WRITE or PERSONS_READ instance.

Did you write or update any docs for this change?

• [ ] I've added or updated the docs
• [ ] I've reached out for help from the docs team
• [X] No docs needed for this change

How did you test this code?

Covered by existing tests.