Disabled appstore in config.php still access the store

[Gomez]

Steps to reproduce

1. Add 'appstoreenabled' => false to config.php
2. Access https://cloudurl.com/settings/apps

Expected behaviour

Only apps that exits on the filesystem should be installable. No other category than "Enabled" and "Not enabled" should be shown. (Like in Nextcloud 10)

Actual behaviour

Many categories are shown like Files, Multimedia ...
All Apps from the store are shown.

Server configuration

Nextcloud version: (see Nextcloud admin page)
Version 11.0.0 (git)

Updated from an older Nextcloud/ownCloud or fresh install:
Fresh

Where did you install Nextcloud from:
GIT

[Gomez]

Related #2701

[Gomez]

Thanks to @nickvergessen just a "return [];" in https://github.com/nextcloud/server/blob/master/lib/private/App/AppStore/Fetcher/Fetcher.php#L97 solves it.

I will create a proper PR.

[MorrisJobke]

Fix is in #3287