fix: use alternative getFoldersForGroups method instead of removed getFoldersForGroup method

[saw-jan]

Description

Method getFoldersForGroup was recently removed in the master branch of groupfolders. See nextcloud/groupfolders#3883
Use the existing alternative method: getFoldersForGroups which returns the same return type and the only difference is that how we provide the group.

- getFoldersForGroup($groupId);
+ getFoldersForGroups([$groupId]);

Compatible with nextcloud:

• master
• stable31
• stable30

Related Issue or Workpackage

• Fixes the failing CI https://github.com/nextcloud/integration_openproject/actions/runs/17026427055/job/48262366973

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Tests only (no source changes)

Checklist:

• Code changes
• Unit tests added
• Acceptance tests added
• Updated CHANGELOG.md file

[individual-it]

so now we need to check that nobody is running the old version of the group-folder app

[saw-jan]

so now we need to check that nobody is running the old version of the group-folder app

we should be immune to that. using getFoldersForGroups is supported in groupfolder stable28 branch as well.

[nabim777]

LGTM 👍

[saw-jan]

so now we need to check that nobody is running the old version of the group-folder app

but there will be a problem if we use the older version of the integration_op app with the new version of the groupfolders app

[github-actions]

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