Write tempest-multinode-full as zuulv3 native

Rewrite the base tempest multinode job as zuulv3.
The job is currently hosted in the neutron repo as
neutron-tempest-multinode-full.

Full job name history:
* neutron-tempest-multinode-full
* legacy-tempest-dsvm-neutron-multinode-full
* gate-tempest-dsvm-neutron-multinode-full-ubuntu-xenial-nv

With this patch, devstack-tempest can be used as a basis for both
single and multinode jobs.

Depends-on: https://review.openstack.org/561187
Depends-on: https://review.openstack.org/561251
Depends-on: https://review.openstack.org/564220
Depends-on: https://review.openstack.org/572313

Change-Id: If448ae20bca6e221b4a10646c69ba014656438ad
diff --git a/playbooks/post-tempest.yaml b/playbooks/post-tempest.yaml
index 4dde2c9..6e0bcad 100644
--- a/playbooks/post-tempest.yaml
+++ b/playbooks/post-tempest.yaml
@@ -1,4 +1,4 @@
-- hosts: all
+- hosts: tempest
   become: true
   roles:
     - role: fetch-subunit-output