Fix trusted domain users/groups error message in legacy UI
Have a truenas customer that has joined their appliance to their domain.
They have a primary domain (CISD) and then 2 trusted domains (EMPLOYEES, STUDENTS)
In the webUI, when trying to change the dataset's owner/group permissions and use an account from one of the trusted sites (i.e. EMPLOYEES\username) it will fail with an error message stating ("The user username is not valid")