Test fixes

These are different commits that fix some Elastic-Search related tests.

All of them are *not* fixed yet, because we have some leaks from one test to another (tests not cleaning after themselves).

There is a particular change I would need to have reviewed: the removal of the search for author prefixes, when doing a search. I didn't managed to understand why this was failing, but removing this bit made the tests pass; so I'm not sure this is the fix we want.