DBT_SPLITS_THE_DATASETS_OUT is a BigQuery Dataset name that does not exist. So, the default is being picked up while the entry for some-project is what is picked up by the test.

someProject:
  common_profile: &common_profile
    type: bigquery
    method: oauth
    location: us-east4
    dataset: DBT_SPLITS_THE_DATASETS_OUT
    threads: 16
    job_execution_timeout_seconds: 300
    job_retries: 1
    priority: interactive
  outputs:
    default:
      <<: *common_profile
      project: "{{ env_var('GCLOUD_PROJECT') }}"
    some-project:
      <<: *common_profile
      project: some-project