Searching for share recipients with search terms <= 2 characters fails

[JammingBen]

Describe the bug

Searching for share recipients with search terms that are <= 2 characters fails for non-admins.

Steps to reproduce

1. As non-admin user, upload a file
2. Open the right sidebar sharing panel
3. Search for "ma"

Expected behavior

The dialog shows all found users/groups or "No results".

Actual behavior

The loading spinner never ends because the server responds with a 403 error.

Issue only exists on master due to sharing NG.

[JammingBen]

Maybe not a Web issue at all, see https://github.com/owncloud/ocis/issues/9000.