Error message while adding idrange with untrusted domain
    
    While trying to add idrange with untrusted domain name error
    message is misleading.
    
    Changing the error message to:
    invalid 'ID Range setup':Specified trusted domain
    name could not be found.
    
    Resolves: https://pagure.io/freeipa/issue/5078
    Reviewed-By: Alexander Koksharov <akokshar@redhat.com>