Restore SUSE tests to gate

We can build SUSE in the container after the switch in
Ieaf07438c145ba609d4d7b9a055e91b894eca6d9.

Let's start non-voting and promote when we feel it's stable.

Change-Id: Ibe997d3167dc918fcdb28cf065c50049943dd86a

.zuul.d/jobs.yaml

@@ -356,7 +356,6 @@
       Test building and booting an openSUSE 15.x image with Nodepool
       and OpenStack
     parent: dib-nodepool-functional-src-base
-    nodeset: ubuntu-xenial  # Bionic lacks zypper
     vars:
       nodepool_diskimage:
         base_element: opensuse-minimal
@@ -369,7 +368,6 @@
       Test building and booting an openSUSE tumbleweed image with
       Nodepool and OpenStack
     parent: dib-nodepool-functional-src-base
-    nodeset: ubuntu-xenial  # Bionic lacks zypper
     vars:
       nodepool_diskimage:
         base_element: opensuse-minimal

.zuul.d/project.yaml

@@ -17,6 +17,12 @@
         - dib-nodepool-functional-openstack-fedora-31-src
         - dib-nodepool-functional-openstack-ubuntu-xenial-src
         - dib-nodepool-functional-openstack-ubuntu-bionic-src
+        # NOTE(ianw): 2020-04-22 these have been out of the gate for a
+        # while; promote to voting after some stability.
+        - dib-nodepool-functional-openstack-opensuse-15-src:
+            voting: false
+        - dib-nodepool-functional-openstack-opensuse-tumbleweed-src:
+            voting: false
         - dib-functests-centos7-python2
         - dib-functests-centos7-python2-image
         - dib-functests-centos7-python2-extras
@@ -62,12 +68,5 @@
         - dib-nodepool-functional-openstack-gentoo-src
         - dib-nodepool-functional-openstack-debian-stretch-src
         - dib-nodepool-functional-openstack-debian-buster-src
-        # NOTE(ianw): 2019-12-10 : this can not build on bionic due to
-        # no zypper; but devstack has dropped Xenial support so can't
-        # build there either.  Because devstack install in pre, it
-        # causes multiple retries in zuul, so can't be non-voting.
-        # Paused until we figure out what to do.
-        - dib-nodepool-functional-openstack-opensuse-15-src
-        - dib-nodepool-functional-openstack-opensuse-tumbleweed-src
         - octavia-v1-dsvm-scenario
         - octavia-v1-dsvm-py3x-scenario