Don't create bell if user withdraws store request

What does this MR do?

Since !1648 (merged) rejecting and withdrawing store requests is done by the same rest endpoint. As pointed out in beta testing (https://gitlab.com/foodsharing-dev/foodsharing-beta-testing/-/issues/20) withdrawing still creates a bell that the user was rejected. This removes that bell.

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

Very sure

How to test

See the steps in https://gitlab.com/foodsharing-dev/foodsharing-beta-testing/-/issues/20

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
• use "state:" labels to track this MR's state until it was beta tested
• added an entry to CHANGELOG.md
• add 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 Beta Testing Repo :
  • 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

• Wenn Benutzer ihre Anfrage für ein Betrieb selbst zurückziehen, wird keine Glocke erzeugt, das ihre Anfrage abgelehnt wurde.