Add openstack/placement as a required project for heat-grenade*

In order to get openstack/placement installed as part of the
heat grenade jobs, we have to list it as a required project.

Needed by https://review.openstack.org/604454/

Change-Id: I58fae5f56fdbcb4fc084689bde95f1a2c4bfad0f

.zuul.yaml

@@ -77,6 +77,10 @@
       - openstack-infra/devstack-gate
       - openstack/heat
       - openstack/heat-tempest-plugin
+      # openstack/placement is not part of legacy-dsvm-base because that is
+      # branchless and openstack/placement only has a master branch (it is
+      # new as of Stein)
+      - openstack/placement
     irrelevant-files:
       - ^(test-|)requirements.txt$
       - ^.*\.rst$

playbooks/devstack/grenade/run.yaml

@@ -42,6 +42,9 @@
           set -x
           export PROJECTS="openstack-dev/grenade $PROJECTS"
           export PROJECTS="openstack/heat-tempest-plugin $PROJECTS"
+          # Grenade needs to clone the placement repo on the Stein side since
+          # the repo did not exist in Rocky.
+          export PROJECTS="openstack/placement $PROJECTS"
           export PYTHONUNBUFFERED=true
           export GRENADE_PLUGINRC="enable_grenade_plugin heat https://git.openstack.org/openstack/heat"
           export DEVSTACK_GATE_NEUTRON=1