Fix BatchOperator links on wait_for_completion = True

[Taragolis]

Fix incidentally wrong usage of list.extend method in operator_extra_links property of BatchOperator

Broken DAG: [/files/dags/example_batch.py] Traceback (most recent call last):
  File "/opt/airflow/airflow/serialization/serialized_objects.py", line 658, in _serialize_node
    if op.operator_extra_links:
  File "/opt/airflow/airflow/providers/amazon/aws/operators/batch.py", line 118, in operator_extra_links
    op_extra_links.extend(BatchJobDefinitionLink(), BatchJobQueueLink())
TypeError: extend() takes exactly one argument (2 given)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/opt/airflow/airflow/serialization/serialized_objects.py", line 1125, in to_dict
    json_dict = {"__version": cls.SERIALIZER_VERSION, "dag": cls.serialize_dag(var)}
  File "/opt/airflow/airflow/serialization/serialized_objects.py", line 1033, in serialize_dag
    raise SerializationError(f'Failed to serialize DAG {dag.dag_id!r}: {e}')
airflow.exceptions.SerializationError: Failed to serialize DAG 'example_batch_submit_job_2': extend() takes exactly one argument (2 given)

[josh-fell]

@Taragolis Have you happened to use the BatchOperator with Dynamic Task Mapping? The reason I ask is there was a previously reported issue with operator links declared this way and it breaking dynamically mapped tasks. There are some fixes out there as well: #24676 and #25215.

Going to block this in the meantime.

[josh-fell]

Holding off on merging this for a response on Dynamic Task Mapping impact. However, if anyone feels strongly, we can merge this and look at a fix (if one is needed) as a fast-follow perhaps?

[Taragolis]

I thought it required changes in DAG serialisation, if attribute is property it is required get actual value of property rather than object and only affect serialisation error for Dynamic Task Mapping since Airflow 2.3.

I could also look on issue related to DAG serialisation (separate PR), however this PR fix general Operator issue.

[josh-fell]

I did a quick test. Definitely the same serialization issue. See #25243.

[josh-fell]

I thought it required changes in DAG serialisation, if attribute is property it is required get actual value of property rather than object and only affect serialisation error for Dynamic Task Mapping since Airflow 2.3.

I could also look on issue related to DAG serialisation (separate PR), however this PR fix general Operator issue.

No worries! Just curious if you had tried it. Good points. The issue can be tackled later.