Fix(Model): fix clean function

[stonebuzz]

Checklist before requesting a review

Please delete options that are not relevant.

• [ ] I have performed a self-review of my code.
• [ ] I have added tests (when available) that prove my fix is effective or that my feature works.
• [ ] I have updated the CHANGELOG with a short functional description of the fix or new feature.
• [ ] This change requires a documentation update.

Description

• It fixes #540

Revert change introduced by glpi 11 compatibility PR

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