Apply dedent when docstring is passed as task doc

### Description When using task decorator, task documentation can be passed using via the function docstring like this ```python @task(task_display_name="My task") def my_task(**context): """ This task do ... In case of error you should do ... """ ``` Unfortuntally, since no dedent is applied the display in the user interface is unattractive. It's possible to achieve a good result by removing the indentation from the DAG file, but this makes the code less readable. ### Use case/motivation _No response_ ### Related issues _No response_ ### Are you willing to submit a PR? - [ ] 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)