Fix warning message about blocked aria-hidden on an element and navigation in dialogue

Describe the bug
When I want to duplicate a meeting in a committee and as soon as the overlay dialogue opens, the console gets the following warning message:

Additionally, I can't navigat the selection in the dialogue with keys and enter. Instead enter opens the context menu with the duplicate button:

How to Reproduce

1. open a comiittee
2. open the console
3. click on duplicate a meeting -> warning message in the console
4. click enter -> navigate to context menu

(The warning does not always appear. In case it doesn't, please reload after step 1 and repeat.)

Expected behavior
No warning message during meeting duplicate (and set template/archive/delete) and it should be possible to navigate to "Ok" and "Cancel"

Same problem for other dialogue:

• numbering of agenda (> meeting > agenda > 3-point-menu > numbering)
• mandate swap

Additional info
Other overlay dialogues may be affected as well. Please check if you can fix it for all cases.

Reproduce the issue by opening a committee, duplicating a meeting, and checking the console and keyboard focus in the dialogue. Inspect the overlay dialogues used for meeting duplicate, template/archive/delete, agenda numbering, and mandate swap; done means no aria-hidden warning and keyboard navigation reaches Ok and Cancel in all affected cases.