Fix AWS Batch Executor compatibility with Airflow 3 in try_adopt_task_instances

[ambaena]

Related: #62192

The AWS Batch Executor still calls TaskInstance.command_as_list() from try_adopt_task_instances(). That method is not available in Airflow 3 after the Task SDK changes.

This is triggered when the scheduler restarts or fails over and tries to adopt orphaned task instances that still have an external_executor_id pointing to an AWS Batch job. The scheduler calls adopt_or_reset_orphaned_tasks(), the Batch executor describes the existing Batch jobs, and then crashes while rebuilding the command for the adopted task instance:

AttributeError: TaskInstance object has no attribute command_as_list

The normal submission path already handles Task SDK workloads. This change makes the adoption path use the same Task SDK command serialization on Airflow 3 while keeping the existing command_as_list() behavior for Airflow 2.

This mirrors the ECS executor fix from #62192 for the AWS Batch executor.

Testing:

• prek run --files providers/amazon/src/airflow/providers/amazon/aws/executors/batch/batch_executor.py providers/amazon/tests/unit/amazon/aws/executors/batch/test_batch_executor.py
• uv run --project providers/amazon pytest providers/amazon/tests/unit/amazon/aws/executors/batch/test_batch_executor.py -k "try_adopt_task_instances or serialize_workload_to_command or build_task_command" -xvs

Disclosure: I used an AI assistant to help investigate the failure mode and cross-check the proposed fix. I reviewed the final code and tests myself.

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[ambaena]

Fixed the test failure caused by Python 3.10 compatibility.