Revert docker-compose to registry

What does this MR do?

Revert a change to reduce building times and ci complications.

• removed docker/build
• removed docker/conf/nginx and docker/conf/db
• adjusted configs in docker/conf/php to better match FS_PLATFORM
• uses images from gitlab.com/foodsharing-dev/images
• removed docker/docker-compose.ci.yml is not in use
• added configurations hints in docker/docker-compose.yml

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

🤷

Links to related issues

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
• 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