Setting DATACONTRACT_BIGQUERY_BILLING_PROJECT causes test failures

[kien-truong]

When DATACONTRACT_BIGQUERY_BILLING_PROJECT is set, the project configuration in servers are ignored and all tests use the value of DATACONTRACT_BIGQUERY_BILLING_PROJECT as the BigQuery datasets project, causing test failures.

[kien-truong]

This is because for ibis, you probably need to set the catalog value to the BigQuery server's project, otherwise it'd use the default credential project_id.

https://ibis-project.org/backends/bigquery#ibis.backends.bigquery.Backend.list_databases

[jochenchrist]

related: #1291

[jochenchrist]

What would be your expected behavior?

[kien-truong]

The correct behavior is as described in ticket #1291
However, pr #1292 that closed it doesn't work correctly, and it also doesn't have any validation tests.