Remove `default_view` property from DAG class and model
This doesn't make sense in the new UI in Airflow 3 anymore.
Relates to #43519
(Yes, this def needs a news fragment, and likely a rule in our Ruff checks)
cc @uranusjr @Lee-W (I think you are working on ruff rules)
Do we want to remove dag_default_view from the airflow config at the same time or in another PR?
cc @uranusjr @Lee-W (I think you are working on ruff rules)
Thanks for reminding us 🙌 I'll add a rule once merged
(If someone wants to finish this off before I'm back on week starting 6th January feel free.)