BigQueryInsertJobOperator may start the same job twice

[hsej]

Apache Airflow version: 1.10.15

Apache Airflow Provider versions (please include all providers that are relevant to your bug):
apache-airflow-backport-providers-google==2021.3.3

What happened:
Looking at the _submit_job method the job is started by using job.result() - in bold below. However, the job IS already started by just callnig the hook.insert_job() method. Thus I suggest removing the extra job.result() call in the _submit_job() method below.

    def _submit_job(
        self,
        hook: BigQueryHook,
        job_id: str,
    ) -> BigQueryJob:
        # Submit a new job
        job = hook.insert_job(
            configuration=self.configuration,
            project_id=self.project_id,
            location=self.location,
            job_id=job_id,
        )
        # Start the job and wait for it to complete and get the result.
        **job.result()**
        return job

[boring-cyborg]

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[hsej]

Sorry!

Thank you very much for that.

[uranusjr]

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