only boot apps once
only boot apps once

in some cases `loadApp` is called more then once which is currently causing apps to be "booted" multiple times which can lead to unexepected behaviour with things like registering hooks

Signed-off-by: Robin Appelman <474ee9ee179b0ecf0bc27408079a0b15eda4c99d@icewind.nl>

andreas-p/nextcloud-server,andreas-p/nextcloud-server,nextcloud/server,andreas-p/nextcloud-server,nextcloud/server,nextcloud/server,andreas-p/nextcloud-server,nextcloud/server,andreas-p/nextcloud-server