Resolve "clean script does not clear tests"

Closes #1027 (closed)

What does this MR do?

Fixed multiple bugs in clean script. Test Containers were not removed properly and upload folder was not emptied.

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

Does only affect local dev environments. I'm pretty sure the clean script will not be used in deployment.

How to test

1. Checkout branch locally
2. Run scripts/test
3. Run scripts/clean
4. All foodsharing containers should be gone.

No testing is needed as it is for cleanup of dev environment.

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

Not applicable.