Help to update IRM users on the Studio service

Steps to reproduce:

1. Go to this Studio service **https://connect.nuxeo.com/nuxeo/nxpath/default/default-domain/connectRoot/clients/Iron%20Moutain/services/6365474560189400490@view_documents
2. Edit
3. Removing all the users (but the StudioUsers group)
4. Save
5. After a while, there is a timeout error ("504 Gateway Time-out") and the service is not saved with the changes

Expected behavior: the service is saved without error