Fix two-node job configuration

Two-node job was failing because devstack tried to compile the
test_server.go file on controller2.
controller2 doesn't have tempest installed, but octavia-tempest-plugin
was installed. The compilation step was failing and is not necessary
there.

Fix octavia-v2-act-stdby-dsvm-scenario-two-node definition, overrides
were not applied.
Fix the "zuul_copy_output" section.

Move to ML2/OVN backend.

Co-Authored-By: Carlos Goncalves <cgoncalves@redhat.com>
Change-Id: I24976e93e9ea8f7f50c9da014c2627965512893c
diff --git a/playbooks/prepare-ovn-multinode.yaml b/playbooks/prepare-ovn-multinode.yaml
new file mode 100644
index 0000000..a653a6c
--- /dev/null
+++ b/playbooks/prepare-ovn-multinode.yaml
@@ -0,0 +1,4 @@
+- hosts: all
+  roles:
+    - multi-node-bridge
+    - multi-node-setup