ATM Special:MediaSearch uses an api that wraps the search api
When https://phabricator.wikimedia.org/T252685 is merged we need to change Special:MediaSearch to use the new backend. ATM the new backend will only be activated if mediasearch=1 is in the request url, and the search is in the File namespace
Acceptance criteria:
- Special:MediaSearch uses MediaQueryBuilder (possibly via the search api) instead of making multiple calls to the search api using haswbstatement etc
This is not something that can be QAd, except for to make sure nothing has broken