Unauthenticated users can access Cryptpad instance

[js-ddev]

Test with the OpenDesk project deployment, on Kubernetes cluster with NextCloud sync, and OpenID authentication.

Step to reproduce:

• Log to the platform, access a diagram file on NextCloud
• copy the URL of the diagram and open it in a private window
• Expected result: unregistered user will have credentials required
• Current result: unregistered user can access and download the diagram: