The new version of Zotero's translation server does not (yet) support exporting references to bibtex, so we need to remove it from the public API.
This was all due to our automated checking infrastructure which requested bibtex. After [removing it from spec.yaml](https://gerrit.wikimedia.org/r/#/c/mediawiki/services/citoid/+/451835/) all of the bibtex request went away. Therefore, no external clients are actually using bibtex.
This is very interesting info. Nevertheless, I reopened the ticket for now. Let's keep our eyes on the resolution of the issue, and if exporting is ready by the time we are ready to deploy zotero v2, we can keep bibtex. Alternatively, we can re-add it once it's ready on their side if it happens to be after our deployment.