Issue Summary

Starting on JSM 4.19, when users are with 'Assignable User' permission but NOT with service desk role, the user is showed in user picker but cannot have the tickets assigned.

The expectation, as the user is not in a role that can assign tickets, is the users not shown in user picker auto complete or search.

This is reproducible on Data Center: yes

Steps to Reproduce

1. In an 4.19+ environment create users
2. Create a group and assign the users to the group
   
3. In Project Settings > Permission add the group to 'Assignable User'
   
4. In Project Settings > User and Roles ensure the group/users are not in roles
   
5. In any JSM ticket go to Assignee field and start typing the username of the user from the group, it will shown and if try to assign the ticket a message will appear indicating the user cannot be assigned issues.
   
   

Expected Results

Neither have the users appearing in Assignee user pick nor give the possibility to assign.

Actual Results

The unexpected users are shown as well as can try to assign the ticket to them, resulting in error.

Workaround

Remove the unnecessary group/users from 'Assignable User' permission.