Airflow upgrade MR 5/5
You will find here:
- the creation of the deb package through the Gitlab-CI
- the creation & use of a dependencies lock file
- the code adaptations to Airflow 2.5.0 (config, dags, dev instance)
Deprecates: https://gerrit.wikimedia.org/g/operations/debs/airflow Bug: https://phabricator.wikimedia.org/T326193
(Previous draft MR: !164 (closed))