Remove duplicate concept IDs

[StepanBrychta]

Part of: #5781

There are many concepts which have several canonical IDs associated with them. This prevents us from switching to ID-based filtering/aggregations on search pages because each of the canonical IDs would have its own aggregation bucket, leading to duplicate concept labels in filtering dropdowns in the frontend.

We should investigate why these duplicate IDs were minted and try to get rid of them. Ideally we want to get to a point where every concept only has one canonical ID associated with it. In other words, we want to reach a point where the display.sameAs field of each concept indexed in the concepts-store index is empty.