Fix legacy-api-ref job

- Add missing project openstack/requirements
- Copy results from correct location

Change-Id: Ie21ed5c5d40f1bf447c36532426d08ca6c01252a

playbooks/legacy/api-ref/post.yaml

@@ -3,7 +3,7 @@
 
     - name: Copy files from api-ref/build/html/ on node
       synchronize:
-        src: api-ref/build/html/
+        src: '{{ ansible_user_dir }}/workspace/api-ref/build/html/'
         dest: '{{ zuul.executor.log_root }}/html/'
         mode: pull
         copy_links: true

zuul.d/zuul-legacy-jobs.yaml

@@ -194,6 +194,8 @@
     post-run: playbooks/legacy/api-ref/post
     timeout: 1800
     branches: master
+    required-projects:
+      - openstack/requirements
     files:
       - ^tox.ini$
       - ^api-ref/.*