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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 -->


DataflowJobStatus.JOB_STATE_FAILED,
                "Google Cloud Dataflow job name-2 has failed\\.",
            ),
            (
                DataflowJobType.JOB_TYPE_STREAMING,
                DataflowJobStatus.JOB_STATE_UNKNOWN,
                "Google Cloud Dataflow job name-2 was unknown state: JOB_STATE_UNKNOWN",
            ),
            (
                DataflowJobType.JOB_TYPE_BATCH,
                DataflowJobStatus.JOB_STATE_UNKNOWN,
                "Google Cloud Dataflow job name-2 was unknown state: JOB_STATE_UNKNOWN",
            ),
            (
                DataflowJobType.JOB_TYPE_BATCH,
                DataflowJobStatus.JOB_STATE_CANCELLED,
                "Google Cloud Dataflow job name-2 was cancelled\\.",
            ),
            (
                DataflowJobType.JOB_TYPE_STREAMING,
                DataflowJobStatus.JOB_STATE_CANCELLED,
                "Google Cloud Dataflow job name-2 was cancelled\\.",
            ),
            (
                DataflowJobType.JOB_TYPE_BATCH,
                DataflowJobStatus.JOB_STATE_DRAINED,
                "Google Cloud Dataflow job name-2 was drained\\.",
            ),
            (
                DataflowJobType.JOB_TYPE_STREAMING,