[CI] Fix placement-nova-tox-functional-py37 job

Patch I1d6a2986fcb0435cfabdd104d202b65329909d2b removed job definition
of nova-tox-functional-py37 job from nova, and now that is missing for
placement-nova-tox-functional-py37 job. This patch uses
openstack-tox-functional-py37 as parent and sets up the job.

Change-Id: I2b70f34fa5387bb13caabdc8b1a1133271cb40d3

.zuul.yaml

@@ -58,14 +58,26 @@
 
 - job:
     name: placement-nova-tox-functional-py37
-    parent: nova-tox-functional-py37
+    parent: openstack-tox-functional-py37
     description: |
         Run the nova functional tests to confirm that we aren't breaking
         the PlacementFixture.
+    required-projects:
+      # including nova here makes this job reusable by other projects
+      - openstack/nova
+      - openstack/placement
+    irrelevant-files:
+      - ^.*\.rst$
+      - ^api-.*$
+      - ^doc/(source|test)/.*$
+      - ^nova/locale/.*$
+      - ^releasenotes/.*$
     vars:
         # 'functional-without-sample-db-tests' tox env is defined in nova tox.ini
         # to skip the api|notification _sample_tests and db-related tests.
         tox_envlist: functional-without-sample-db-tests
+        bindep_profile: test py37
+    timeout: 3600
 
 - job:
     name: placement-perfload