During the discussions around page previews deployment, most enwiki and dewiki participants preferred a configuration where previews are off for existing editors and on for new accounts.
== Acceptance criteria
 Allow page previews to be on by default for new accounts on a per-wiki basis
 This will be deployed in a separate task
== Signoff criteria
 Inform all wikis of upcoming change
 Set up deployment task
= Developer notes
The https://www.mediawiki.org/wiki/Manual:Hooks/LocalUserCreated hook runs when in account is created. With the provided user set a user preference.
I assume we can ignore doing this for accounts where $autocreated is set to true.