`occ files:scan` scans the same group folders for every user

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

I have noticed that running occ: files:scan includes whatever group folders the user is a member of as well.

This makes for incredibly slow scanning, especially if you have 30+ users and use the --all option. The same group folders are scanned over 30 times.

Steps to reproduce

1. Run occ files:scan on an installation with multiple users belonging to the same group folders.

Expected behavior

Group folders should be scanned separately to avoid the files:scan --all command scanning the same files over and over.

Installation method

No response

Operating system

No response

PHP engine version

No response

Web server

No response

Database engine version

No response

Is this bug present after an update or on a fresh install?

No response

Are you using the Nextcloud Server Encryption module?

No response

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

No response

List of activated Apps

Enabled:
  - accessibility: 1.8.0
  - activity: 2.15.0
  - admin_audit: 1.12.0
  - circles: 22.1.1
  - cloud_federation_api: 1.5.0
  - comments: 1.12.0
  - contactsinteraction: 1.3.0
  - dashboard: 7.2.0
  - dav: 1.19.0
  - deck: 1.5.5
  - federatedfilesharing: 1.12.0
  - federation: 1.12.0
  - files: 1.17.0
  - files_pdfviewer: 2.3.1
  - files_rightclick: 1.1.0
  - files_sharing: 1.14.0
  - files_trashbin: 1.12.0
  - files_versions: 1.15.0
  - files_videoplayer: 1.11.0
  - firstrunwizard: 2.11.0
  - groupfolders: 10.0.0
  - logreader: 2.7.0
  - lookup_server_connector: 1.10.0
  - nextcloud_announcements: 1.11.0
  - notifications: 2.10.1
  - oauth2: 1.10.0
  - password_policy: 1.12.0
  - photos: 1.4.0
  - privacy: 1.6.0
  - provisioning_api: 1.12.0
  - recommendations: 1.1.0
  - serverinfo: 1.12.0
  - settings: 1.4.0
  - sharebymail: 1.12.0
  - support: 1.5.0
  - survey_client: 1.10.0
  - systemtags: 1.12.0
  - text: 3.3.0
  - theming: 1.13.0
  - twofactor_backupcodes: 1.11.0
  - twofactor_totp: 6.2.0
  - updatenotification: 1.12.0
  - user_status: 1.2.0
  - viewer: 1.6.0
  - weather_status: 1.2.0
  - workflowengine: 2.4.0
Disabled:
  - encryption
  - files_external
  - user_ldap

Nextcloud Signing status

No response

Nextcloud Logs

No response

Additional info

No response

Start by tracing the occ files:scan entry point in the groupfolders integration and how --all handles users and shared group folders. Reproduce the scan with multiple users sharing a group folder, then verify that each group folder is scanned once rather than once per member.