Remove apps delivered from the appstore

Apps that are in shipped.json follow some more requirements such as having a valid code integrity check. This is not something that we require when they come from the appstore as there we verify the download integrity via the signature.

Also the updater treats apps that are shipped differently. We should however handle the apps like any other app from the appstore.

Fixes https://github.com/nextcloud/server/issues/4605



Signed-off-by: Lukas Reschke <lukas@statuscode.ch>