Fix airflow_db_cleanup script

[khokharnikunj8]

Description

Fixes b/223364117
The DAG is now able to perform cleanup operation on airflow databases with larger data in a single table.
More context : http://docs/document/d/1eWydWjGXqqQ4lvACOMs5o7qQtnuuyo_0jzwWXJ3_YfY?resourcekey=0-TBb9afCO5cWD5hhW_sRZgQ
Note: It's a good idea to open an issue first for discussion.

Checklist

• I have followed Sample Guidelines from AUTHORING_GUIDE.MD
• README is updated to include all relevant information
• Tests pass: nox -s py-3.6 (see Test Environment Setup)
• Lint pass: nox -s lint (see Test Environment Setup)
• These samples need a new API enabled in testing projects to pass (let us know which ones)
• These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• Please merge this PR for me once it is approved.
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample

[dandhlee]

Reviewing for sample reviewers. Please fix the lint error as well.

[leahecole]

Please give python-samples-reviewers@ access to the doc with context.

Also, does this affect only Airflow 1, or do we need to make these changes in https://github.com/GoogleCloudPlatform/python-docs-samples/blob/main/composer/workflows/airflow_db_cleanup.py as well?

[khokharnikunj8]

Please give python-samples-reviewers@ access to the doc with context.

Also, does this affect only Airflow 1, or do we need to make these changes in https://github.com/GoogleCloudPlatform/python-docs-samples/blob/main/composer/workflows/airflow_db_cleanup.py as well?

Hi, Currently we aim to fix the script for Airflow version 1. We will soon update the script for Airflow version 2 in the later phases.

Gave access to the document to python-samples-reviewers@.

Thanks!

[leahecole]

If @dandhlee 's concerns are addressed, LGTM

[dandhlee]

One last edit!

[dandhlee]

LGTM!