Pull requests to v9 are all blocked

[leagrdv]

Since the update to Angular 20 on v9, all PRs are now blocked because the E2E tests are not running.
From what I got from Alona, the plan would be to remove the demo app from v9 (Philipp had started working on that on PR #6099), but something still needs fixing on the intranet-header package.

[oliverschuerch]

We fixed this issue by reverting the Angular@20 update.
Therefore it's not a valid case anymore.

Instead we have added the ticket to update Angular in the future, which could be merged maybe.

• #5569

[alizedebray]

Angular 20 update was reverted on the release/v9 branch.