Use Api for deleting wallposts

Part of removing old Xhr (#798 (closed))

What does this MR do?

Wall posts are not delete by Xhr anymore, but by the existing rest api.

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

Very sure

How to test

1. Checkout branch locally
2. Login as foodsaver
3. Open your own profile page
4. Write something on the wall
5. Delete the post again

Checklist

• added a test, or explain why one is not needed/possible... -> already covered
• 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