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**Description**

Related to the discussion here: https://github.com/apache/airflow/pull/8553#discussion_r416136954

Allow user to define expected terminal state. e.g. `JOB_STATE_CANCELLED` could be not treated as failure but expected terminal state.


<!-- A short description of your feature -->


with pytest.raises(RuntimeError):
            AsyncDataflowHook(gcp_conn_id="GCP_CONN_ID", delegate_to="delegate_to")
    @pytest.fixture
    def hook(self):
        return AsyncDataflowHook(
            gcp_conn_id=TEST_PROJECT_ID,
        )
    @pytest.mark.asyncio
    @mock.patch("airflow.providers.google.cloud.hooks.dataflow.AsyncDataflowHook.initialize_client")
    async def test_get_job(self, initialize_client_mock, hook, make_mock_awaitable):
        client = initialize_client_mock.return_value
        make_mock_awaitable(client.get_job, None)
        await hook.get_job(
            project_id=TEST_PROJECT_ID,
            job_id=TEST_JOB_ID,
            location=TEST_LOCATION,
        )
        request = GetJobRequest(
            dict(
                project_id=TEST_PROJECT_ID,
                job_id=TEST_JOB_ID,
                location=TEST_LOCATION,
                view=JobView.JOB_VIEW_SUMMARY,
            )
        )
        initialize_client_mock.assert_called_once()
        client.get_job.assert_called_once_with(
            request=request,
        )