setup-apps.sh upgrades pinned apps from app store

We pin most of the nextcloud apps we install to a specific version. However, it seems that the occ upgrade that we perform as part of the setup-apps.sh script upgrades apps beyond the pinned version, taking the latest compatible version from the nextcloud app store. That's exactly what we don't want.

Probably this is because we temporarily enable the app store during that part of the script. We do that because we install some apps that have a non-standard upstream source, versioning scheme, or lack package artifacts in the github releases. However I believe that by now we have extended the pinning features in our nextcloud chart to the point where we can get all Stackspin-default apps from upstream (github/gitlab) directly and no longer need the app store at all. If that is true, we can forego temporarily enabling the app store, and that should prevent nextcloud from doing any unwanted upgrades.