Fix ansible dsvm functional job

The job is missing the post_test_hook function export.
This makes the job to bail early, as there's no post test hook
and the cleanup routine is called immediately.

This causes an issue on DevStack, as the cleanup calls the
stackviz installation code which makes a pip install -U, upgrading
underlying libs needed by DevStack like pytz and oslo.context, which
breaks subsequent tests as the latest versions of these libraries
do not work properly with Nova code.
e.g. https://review.openstack.org/#/c/342099/

The tox kickoff script should be in project repo, rather than
relying on the tox macro. The path expected is
tests/hooks/post_test_hook.sh.

Depends-On: Icfe3d5a4f4226d36885664bb95a370ada13c630f
Change-Id: Ie56f41884253d1ab97a205fdb9fbde88963c5fe7

jenkins/jobs/ansible-role-jobs.yaml

@@ -50,10 +50,13 @@
               export OVERRIDE_ZUUL_BRANCH=$BRANCH_OVERRIDE
           fi
 
+          function post_test_hook {{
+              $BASE/new/$ZUUL_PROJECT/tests/hooks/post_test_hook.sh
+          }}
+          export -f post_test_hook
+
           cp devstack-gate/devstack-vm-gate-wrap.sh ./safe-devstack-vm-gate-wrap.sh
           ./safe-devstack-vm-gate-wrap.sh
-      - tox:
-          envlist: functional
 
     publishers:
       - devstack-logs