Deprecate task log prefix

### Apache Airflow version 2.9.0 ### What happened? There is a part of code that may have been dead since airflow 2.0.0 for task logs prefix. The code is extending a StreamHandler which is not being used anywhere. The current local or remote task logs are extending FileTaskHandler. ### What you think should happen instead? Either this should be completely removed from Airflow or fix the feature with FileTaskHandler ### How to reproduce Set `AIRFLOW__LOGGING__TASK_LOG_PREFIX_TEMPLATE` with an example provided in the [docs](https://airflow.apache.org/docs/apache-airflow/stable/configurations-ref.html#task-log-prefix-template). ### Operating System Any ### Versions of Apache Airflow Providers Not Applicable. ### Deployment Docker-Compose ### Deployment details _No response_ ### Anything else? I have raised a PR #38709 in an attempt to make this feature working with FileTaskHandler. Though I understand there might not be any point in bring a dead feature back. So, I'm proposing to remove the config `task_log_prefix_template` all together residing in below code: https://github.com/apache/airflow/blob/f8104325b7a66d4e98ff3a6c3555f90c796071c6/airflow/utils/log/task_handler_with_custom_formatter.py#L36 ### Are you willing to submit PR? - [X] Yes I am willing to submit a PR! ### Code of Conduct - [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)