Move the nova-next job in-tree and update it

This moves the legacy-tempest-dsvm-neutron-nova-next-full
job from openstack-zuul-jobs in-tree and updates a
few things since it's now branch specific:

- The cells v2 and placement stuff can be removed since those
  are required now (they were optional when this job would run
  against newton changes).
- Use nova/gate/post_test_hook.sh rather than the symlink under
  nova/tools/hooks/.

The job is currently non-voting and needs to remain that way
until bug 1747511 is fixed.

According to the branch restrictions in project-config, apparently
this job is only running against stable/newton (which no longer
exists) and master, presumably when master was pike. We should also
run this job against stable/pike for the service user test coverage
and post_test_hook.sh run, so we'll likely backport this change
to stable/pike as well.

The related project-config change is:

I36d96f89b3e5323746fcbcef5cc7e4d0384a184d

Change-Id: I24a5f73c29094a23e2fdef8ee8b43601300af593

.zuul.yaml

@@ -86,11 +86,27 @@
     run: playbooks/legacy/nova-multiattach/run.yaml
     post-run: playbooks/legacy/nova-multiattach/post.yaml
 
+- job:
+    name: nova-next
+    parent: nova-dsvm-base
+    description: |
+      This job was added in Newton when placement and cellsv2
+      were optional. Placement and cellsv2 are required starting in Ocata. In
+      Pike, the service user token functionality was added. This job is also
+      unique in that it runs the post_test_hook from the nova repo, which runs
+      post-test scripts to ensure those scripts are still working,
+      e.g. archive_deleted_rows.
+    # TODO(mriedem): Make this voting once bug 1747511 is fixed.
+    voting: false
+    run: playbooks/legacy/nova-next/run.yaml
+    post-run: playbooks/legacy/nova-next/post.yaml
+
 - project:
     # Please try to keep the list of job names sorted alphabetically.
     check:
       jobs:
         - nova-multiattach
+        - nova-next
         - nova-tox-functional
         - nova-tox-functional-py35
     gate: