Bionic functional tests should be voting

We now have a bionic(-ish ... buster debian image anyway) builder and
have moved some of the important tests (fedora, pip-and-virtualenv) to
here because they don't work on Xenial any more.  This should now be
voting so we don't miss anything.

Change-Id: I16d313e1dfa95707d996456da244667c38d6343f

.zuul.d/jobs.yaml

@@ -95,7 +95,6 @@
       # These can only build on bionic
       dib_functests_extra:
         - fedora-minimal/build-succeeds
-    voting: false
 
 - job:
     name: dib-functests-bionic-python3-image

.zuul.d/project.yaml

@@ -53,6 +53,7 @@
         - dib-nodepool-functional-openstack-ubuntu-bionic-src
         - dib-functests-xenial-python3
         - dib-functests-centos7-python2
+        - dib-functests-bionic-python3
         - ironic-python-agent-check-image-dib-centos8
     experimental:
       jobs: