[Bug]: Python SDK chain after WriteToBigQuery example is incorrect for file_loads method

[tangsiwei0831]

What happened?

In https://github.com/apache/beam/blob/611676d108b26ee378a2b0c128c855017d162772/sdks/python/apache_beam/io/gcp/bigquery.py#L286, the documentation states that the chain operation for file loads is return (result.load_jobid_pairs, result.copy_jobid_pairs) | beam.Flatten()

In fact, according to https://github.com/apache/beam/blob/611676d108b26ee378a2b0c128c855017d162772/sdks/python/apache_beam/io/gcp/bigquery.py#L2230 and https://github.com/apache/beam/blob/611676d108b26ee378a2b0c128c855017d162772/sdks/python/apache_beam/io/gcp/bigquery.py#L2234, it should be return (result.destination_load_jobid_pairs, result.destination_copy_jobid_pairs) | beam.Flatten()

Issue Priority

Priority: 3 (minor)

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