Drop Xenial from functional test

Devstack dropped Xenial support with
Iefcca99904dde76b34efbbfc0e04515dfa5a09e5.

I have ported the required debootstrap in the openstackci PPA to
Bionic, so these builds should work there now.

Unfortunatley, there's no current solution for Suse builds as there is
no zypper for the minimal builds on bionic.  These will either have to
fix that, or figure out how to pin devstack to Train branch for the
jobs.  Since it causes retries in the gate as non-voting, put it in
experimental for now until we figure something out.

Trusty also fails due to issues with ext4 versions using bionic hosts.
This is fixed in a follow-on
Ibd67d58ca830a9e60605d0700ee2b17906c804e6; the job is disabled for now.

Change-Id: I71823236731583e28fddcceb71f44d09b58664a4

.zuul.d/jobs.yaml

@@ -271,7 +271,6 @@
       and OpenStack
     parent: dib-nodepool-functional-src-base
     pre-run: playbooks/dib-nodepool/debootstrap.yaml
-    nodeset: ubuntu-xenial  # Backported debootstrap only available for xenial
     vars:
       nodepool_extra_packages:
         - debootstrap
@@ -287,7 +286,6 @@
       and OpenStack
     parent: dib-nodepool-functional-src-base
     pre-run: playbooks/dib-nodepool/debootstrap.yaml
-    nodeset: ubuntu-xenial  # Backported debootstrap only available for xenial
     vars:
       nodepool_extra_packages:
         - debootstrap
@@ -303,7 +301,6 @@
       and OpenStack (using released libraries)
     parent: nodepool-functional-openstack-base
     pre-run: playbooks/dib-nodepool/debootstrap.yaml
-    nodeset: ubuntu-xenial  # Backported debootstrap only available for xenial
     vars:
       nodepool_debug: true
       nodepool_extra_packages:
@@ -320,7 +317,6 @@
       and OpenStack
     parent: dib-nodepool-functional-src-base
     pre-run: playbooks/dib-nodepool/debootstrap.yaml
-    nodeset: ubuntu-xenial  # Backported debootstrap only available for xenial
     vars:
       nodepool_extra_packages:
         - debootstrap
@@ -348,7 +344,6 @@
       and OpenStack
     parent: dib-nodepool-functional-src-base
     pre-run: playbooks/dib-nodepool/debootstrap.yaml
-    nodeset: ubuntu-xenial  # Backported debootstrap only available for xenial
     vars:
       nodepool_extra_packages:
         - debootstrap
@@ -364,7 +359,6 @@
       and OpenStack
     parent: dib-nodepool-functional-src-base
     pre-run: playbooks/dib-nodepool/debootstrap.yaml
-    nodeset: ubuntu-xenial  # Backported debootstrap only available for xenial
     vars:
       nodepool_extra_packages:
         - debootstrap

.zuul.d/project.yaml

@@ -14,8 +14,7 @@
         - dib-nodepool-functional-openstack-centos-8-src
         - dib-nodepool-functional-openstack-fedora-29-src
         - dib-nodepool-functional-openstack-fedora-30-src
-        - dib-nodepool-functional-openstack-opensuse-15-src
+#        - dib-nodepool-functional-openstack-ubuntu-trusty-src
-        - dib-nodepool-functional-openstack-ubuntu-trusty-src
         - dib-nodepool-functional-openstack-ubuntu-xenial-src
         - dib-nodepool-functional-openstack-ubuntu-bionic
         - dib-nodepool-functional-openstack-ubuntu-bionic-src
@@ -40,8 +39,7 @@
         - dib-nodepool-functional-openstack-centos-8-src
         - dib-nodepool-functional-openstack-fedora-29-src
         - dib-nodepool-functional-openstack-fedora-30-src
-        - dib-nodepool-functional-openstack-opensuse-15-src
+#        - dib-nodepool-functional-openstack-ubuntu-trusty-src
-        - dib-nodepool-functional-openstack-ubuntu-trusty-src
         - dib-nodepool-functional-openstack-ubuntu-xenial-src
         - dib-nodepool-functional-openstack-ubuntu-bionic
         - dib-nodepool-functional-openstack-ubuntu-bionic-src
@@ -53,6 +51,12 @@
         - 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