Make openfoodfacts-events work with local openfoodfacts server

[alexgarel]

Modify docker-compose alike we did in robotoff to make it work with openfoodfacts server locally.

Quirks : I think we should review the settings of all projects to better isolate what is internal to the project (eg. postgresql) to what is exposed (eg the api). For example, currently all postgresql db are named postgres and will conflict badly (docker will round robin over all postgres, leading to really weird errors) if we put them on same network.
This network isolation should be compatible with a preproduction and production deployment.