Fix text for checkbox "Mailversand aktivieren"

Closes #1954 (closed)

What does this MR do?

The text of the checkbox "Mailversand aktiviren" was fixed to only this text.

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

Really sure

Links to related issues

https://foodsharing.freshdesk.com/a/tickets/8172

How to test

1. Checkout branch locally
2. Login as foodsaver
3. Create a new thread in a working group
4. Click the checkbox "Mailversand aktivieren" --> The text shouldn't be changed 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
• set the "API change" label if changes in the API are not backward compatible
• 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 in the release notes to /release-notes/YYYY-MM.md
• Once your MR has been merged, you are responsible to create a testing issue in the Beta Testing forum: https://foodsharing.de/region?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.