An error is thrown when trying to update details of a group of users

Steps to reproduce

Go to the Groups administration page. Click on the cog menu and select Update details, then click on Update. An error occurs.

Investigation

Contrary to its documentation, api/user_groups/search provides a uuid field instead of id. Until we refactor api/user_groups/update to accept a "old name" & "new name" (or something similar), the frontend will need the id from the "search" to provide it to the "update".