The current implementation for concept chips is using WDQS to traverse (and format) related statements.
This does not scale well, and must be removed before a large audience starts to consume the API.
This essentially means these changes in ApiRelatedConcepts::getTermsRelatedToWikibaseItems:
- instead of traversing entity statements via WDQS, we'll only be able use the statements of the matched entities
- this means that we'll lose some heuristics
- heuristics config will likely have to be updated to match above new reality
- and we'll have to add a bit of code to format the statement values (WDQS results already did that, until now)