Add CI step to run prepare provider documentation. (#27832)
Add CI step to run prepare provider documentation. (#27832)

Adds CI step that was likely missing during refactoring when we
run prepare-provider-documentation step to test that it is
still working.

We are running pretty much all our `breeze` commnd in CI even those
that we are using for manual release management, just to make sure
they are still working and that none of the refactorings
break it. This is very reassuring that whenever you attempt to do
the release, most likely the tools that we use for that are still
working.
apache/airflow,apache/airflow,apache/airflow,apache/airflow,apache/airflow,apache/airflow