RelatedArticles is not using the [CardsGateway](https://github.com/wikimedia/mediawiki-extensions-RelatedArticles/blob/master/resources/ext.relatedArticles.cards/CardsGateway.js), instead it reimplemented a [RelatedPagesGateway](https://github.com/wikimedia/mediawiki-extensions-RelatedArticles/blob/master/resources/ext.relatedArticles.readMore.gateway/RelatedPagesGateway.js).
That means that we've been shipping extra unused code, so we should de-duplicate the gateways and keep one.
See related report T137021: Reduce Cards confusion by merging it into RelatedArticles extension (of cards gateway not working that lead to merging cards with relatedarticles).
- There is only one gateway implementation on RelatedArticles
- No extra/unused code is bundled to the client
- Documentation doesn't mention CardsGateway