CI tests should do elasticsearch too

[peterbe]

Searchkit, in the UI, uses Elasticsearch queries to get its data. We should have a full integration test that tests writing to Kinto, which triggers a write to Elasticsearch and then the test should be able to query that data from Elasticsearch.

[peterbe]

Let's depend on #358 first.

[leplatrem]

Maybe we could run the kinto-dist container (that includes https://github.com/Kinto/kinto-elasticsearch) to match what's deployed