Add db cleanup function for easier debugging and testing of dags

### Description

I think that a function that automatically truncates the `Airflow`'s can be beneficial for us to help us combine and manage the state of airflow with [`dag.test` and debugging dags](https://airflow.apache.org/docs/apache-airflow/stable/core-concepts/debug.html).

### Use case/motivation

I want to have a function that I can call using my python code (mostly in my tests) to truncate the whole airflow db locally, it would only work in unit tests mode and on sqlite only (to avoid deleting production db).

### Related issues

_No response_

### Are you willing to submit a 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)

Start by reading the dag.test and debugging DAG documentation linked in the issue, then identify the existing Airflow test-database setup and SQLite-only safeguards. Done means a callable function can safely truncate the local Airflow database in unit-test mode and support repeatable DAG tests and debugging without affecting production databases.

Written by the indexing model from the issue text.