New apps are published as submodules

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### Steps to reproduce
1. Create a new app using the online app generator and download the .tar.gz file
2. Unzip the archive (e.g. `tar xzf ..../app.tar.gz`)
3. Enter the unzipped folder (e.g. `cd helloworld`)
4. Create a git repo from the (e.g. `git init .`)

### Expected behaviour
A git repo should be created, no issues be reported.

### Actual behaviour
Upon creating the new repo, I get
```
fatal: not a git repository: /home/christian/Dokumente/nextcloud-docker-dev/workspace/server/apps-extra/helloworld/../../../.git/modules/nextcloudappstore/scaffolding/helloworld
```

Looking at `.git` in the archive, it is a text file with a submodule link:
```
$ cat .git
gitdir: ../../../.git/modules/nextcloudappstore/scaffolding/helloworld
```

This comes from the fact, that the scaffolding template is inserted as a git submodule as much as I guess.

### Browser

**Browser name:** Firefox

**Browser version:** 139.0.1

**Operating system:** Archlinux

Nothing was logged during browsing the app store. No errors were present or obvious. Just the output data (tar archive) is build in a sub-optimal fashion.