[web/test] Stop testing that exceptions raised in Deferred callbacks call errback
They no longer do as of changeset 7f1f7f710b16.
Related to #5533303.
# -*- coding: utf-8 -*-
# copyright %(year)s %(author)s, all rights reserved.
# contact %(author-web-site)s -- mailto:%(author-email)s
#
%(long-license)s
"""%(distname)s specific hooks and operations"""