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.

Conflicts:
	global-requirements.txt

Change-Id: I561e98bf363d2dd8e8b3a20cea7d2dcbfa034e98
(cherry picked from commit b673b16ac572719cd8552c9cd05448409b628b28)