Let the region chooser forget previous selections

What does this MR do?

Fixes that the region chooser kept showing the selections for lower regions if you change a higher region.

https://yunity.slack.com/archives/C1T1ZM9A4/p1692804242511419

How confident are you it won't break things if deployed?

quite sure

How to test

1. Checkout branch locally
2. Login as foodsaver
3. Open the region chooser
4. Select several nested regions, e.g. Europe -> Germany -> Lower Saxony -> Göttingen
5. Change the top level to something else, e.g. Arbeitsgruppen überregional
6. The lower levels should disappear

Something like this should not be possible anymore:

Checklist

• added a test, or explain why one is not needed/possible...
• no unrelated changes
• asked someone for a code review
• set a "for:" label to indicate who will be affected by this change
• added to the next milestone (see https://gitlab.com/foodsharing-dev/foodsharing/-/milestones, unless it has a "for:Dev" label)
• added an entry to CHANGELOG.md
• added a short text that can be used in the release notes
• Once your MR has been merged, you are responsible to create a testing issue in the Beta Testing forum: https://foodsharing.de/?page=bezirk&bid=734&sub=forum. Please change the MRs label to "state:Beta testing".
  • Consider writing a detailed description in German.
  • Describe in a few sentences, what should be tested from a user perspective.
  • Also mention different settings (e.g. different browsers, roles, ...) how this change can be tested.
  • Be aware, that also non technical people should understand.

Release notes text in German

Behebt, in der Bezirks-Auswahl, wenn eine höherer Bezirk geändert wird, das sich die niedrigeren auch anpassen.