Switch octavia-two-node nodeset to Bionic

Ubuntu Xenial is no longer supported in Devstack. The two-node CI job
fails consistently with:

"WARNING: this script has not been tested on xenial"
"If you wish to run this script anyway run with FORCE=yes"

It is time to update to Ubuntu Bionic.

This patch also removes octavia-v2-dsvm-scenario-ubuntu-bionic from the
check queue as Bionic is now the default Ubuntu version being tested.

Change-Id: Ica2f3289b14b8cdb5437ea3e92bb07a19028e053
diff --git a/zuul.d/jobs.yaml b/zuul.d/jobs.yaml
index 0ed5532..0d68088 100644
--- a/zuul.d/jobs.yaml
+++ b/zuul.d/jobs.yaml
@@ -2,9 +2,9 @@
     name: octavia-two-node
     nodes:
       - name: controller
-        label: ubuntu-xenial
+        label: ubuntu-bionic
       - name: controller2
-        label: ubuntu-xenial
+        label: ubuntu-bionic
     groups:
       - name: controller
         nodes:
diff --git a/zuul.d/projects.yaml b/zuul.d/projects.yaml
index 4445910..be12bba 100644
--- a/zuul.d/projects.yaml
+++ b/zuul.d/projects.yaml
@@ -22,8 +22,6 @@
             voting: false
         - octavia-v2-dsvm-scenario-centos-8:
             voting: false
-        - octavia-v2-dsvm-scenario-ubuntu-bionic:
-            voting: false
         - octavia-v2-act-stdby-dsvm-scenario-two-node:
             voting: false
         - octavia-v2-act-stdby-iptables-dsvm-py2-scenario-stable-rocky: