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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 -->


self,
        body: dict,
        location: str,
        project_id: str,
        on_new_job_id_callback: Callable[[str], None] | None = None,
        on_new_job_callback: Callable[[dict], None] | None = None,
    ) -> dict:
        """
        Starts flex templates with the Dataflow pipeline.
        :param body: The request body. See:
            https://cloud.google.com/dataflow/docs/reference/rest/v1b3/projects.locations.flexTemplates/launch#request-body
        :param location: The location of the Dataflow job (for example europe-west1)
        :param project_id: The ID of the GCP project that owns the job.
            If set to ``None`` or missing, the default project_id from the GCP connection is used.
        :param on_new_job_id_callback: (Deprecated) A callback that is called when a Job ID is detected.
        :param on_new_job_callback: A callback that is called when a Job is detected.
        :return: the Job
        """
        service = self.get_conn()
        request = (
            service.projects()
            .locations()