Prior to deploying page previews to all wikis, we would like to switch to the new summary endpoint so that all users will be able to see html previews
== Pre-task checklist
 Ensure all subtasks are closed before picking up this task.
== Acceptance criteria
 Switch all projects to new summary endpoint
 Perform a full round of QA on feature
 Announce switch (village pumps, wikitech-l)
 Add the deployment to [the Readers Web Release Timeline page](https://www.mediawiki.org/wiki/Reading/Web/Release_timeline).
 Verify fix for T183833: visit https://en.wikipedia.org/wiki/Acetic_anhydride - comment there with a screenshot of what is noticed.