Rename service model to integration

As part of the Mass-integration project, we decided in &2504 (closed) to rename project services to integrations. To reflect the new name, the Service model should be renamed to Integration

QA on staging

Check project import and export continue to work !61210 (comment 572181956)

Export a project from production with active services, and import them to staging. The services should not be imported (existing behaviour) but the import should be successful.

Smoke test services

Existing services that work on staging should continue to work.