insights: always recreate the series on update

Created by: coury-clark

Removes the path that an insight series can be updated instead of replaced. This was causing issues once the unify work was enabled such that series were never regenerating post update. It's not perfect, ideally we would be able to be a bit smarter here and detect changes that don't need a data update.

Test plan

Create a scoped insight and update it, and ensure the new insight reflects the proper query.