Exclude testtools 1.4.0

When running tempest with testtools 1.4.0 attributes aren't being added to the
test_id. This causes the regex excludes we use for the slow tests in tempest to not
work, and the slow jobs get run everywhere, while the slow jobs fail to have any tests. 

Change-Id: I561e98bf363d2dd8e8b3a20cea7d2dcbfa034e98