Airflow Demo: Extend to show 3.x new features

[adwk67]

Description

Airflow 3.x brings with it significant changes to the architecture (UI, services, auth backends etc.) as well as new features. These (new features) do not figure in our demo and it would be good to showcase some of them e.g.

• run a deferred DAG using the triggerer service
• illustrate using a DAG bundle
• incorporate Opa authorisation

Motivation

• tests things not covered by integration tests
• used as a basis for answering support questions
• motivate users to migrate to 3.x+

[lfrancke]

During refinement decide the scope of the demo and the new features to demonstrate.