tests_webui: fix wrong user name key for trail space case
    
    User name for trail space key was using the name for lead space key.
    As a result, when both tests were transformed, second one was
    unsuccessful as the original user was already created.
    
    Fix the user name data according to the test.
    
    Fixes: https://pagure.io/freeipa/issue/8629
    Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>