webui test: Update message for admin disable
An admin can be disabled if he is not the last member of the
admins group. Update the expecrted error message.
Fixes: https://pagure.io/freeipa/issue/9574
Related: https://pagure.io/freeipa/issue/9489
Signed-off-by: Florence Blanc-Renaud <flo@redhat.com>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>