Provide way to override max-joins limit in integration tests

[efgpinto]

From the forums

We currently have a default max number of joins in views set to 3. That limit is enforced even when running locally or for integration tests. When running locally, using VIEW_FEATURE_MAX_JOINS: 4 on the docker-compose ENV vars for the runtime image will make the trick but the same is not possible currently for the integration tests.