nuxeo-user-suggestion in a workflow task displays id only

Studio-side:

1. create a workflow
2. add user variable to the workflow (can contain only users)
3. add 2 approve tasks named Approve (by default) and ApproveB
4. add the user variable to both tasks
5. in Designer, generate the layouts

Server-side:

1. sync the project
2. create a user clageois with firstname Coco and lastname Lageois
3. create a workspace
4. create a File document
5. start the workflow
6. select a user
7. observe the firstname and lastname appear
8. approve the task
9. enter the second task
10. observe the firstname and lastname don't appear, only the id (see attached screenshot)

Expected behavior: the user should be resolved and properly displayed
Note: this is similar to ELEMENTS-834 but with a different scenario.