Remove edx image cache

Description

This MR removes the image caches.

Supporting information

• https://tasks.opencraft.com/browse/SE-6027

Testing instructions

Steps to test the changes:

1. Check the following pipeline that there were no related cache involved
2. Check that the settings below on the pr-613 sandbox are matching:

>>> from django.conf import settings
>>> settings.DUMMY
'hello'
>>>

Dependencies

NA

Screenshots

NA

Checklist

If any of the items below is not applicable, do not remove them, but put a check in it.

• All providers include the new feature/change
• All affected providers can provision new clusters
• Unit tests are added/updated
• Documentation is added/updated
• The TOOLS_CONTAINER_IMAGE_VERSION in ci_vars.yml is updated
• The grove-template repository is updated

Additional context

Add any other context about the merge request here.