Fix execute_async method key parameter type hint in AwsBatchExecutor

[Prab-27]

Fix mypy and remove str from execute_async method key argument
Use TaskInstance class in tests for key instance

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[Prab-27]

OOPs !! it has one more error
working on it !

[amoghrajesh]

@Prab-27 some work is needed:

  suspended_providers  {'apache-airflow-providers-apache-beam'}
  Found 1 error in providers
  Error: The `airflow.providers.amazon.aws.executors.batch.batch_executor.AwsBatchExecutor` object in executors list in providers/amazon/provider.yaml does not exist or is not a class: cannot import name 'BatchJobWorkloadKey' from 'airflow.providers.amazon.aws.executors.batch.utils' (/opt/airflow/providers/amazon/src/airflow/providers/amazon/aws/executors/batch/utils.py)

  Error 1 returned

[Prab-27]

There's already a PR - #67268
Closing !