Disable the tls-proxy in nova-next & fix nova-tox-functional-py35 parent

While moving the legacy job nova-next on bionic, tls-proxy
did not work and leads to nova-next job fail.

To proceed further on Bionic migration which is blocked by nova-next failure,
this commit temporary disable the tls-proxy service until bug#1819794 is fixed.

Also this updates the parent of nova-tox-functional-py35 from openstack-tox
to openstack-tox-functional-py35 in order to handle the upcoming change
of the infra CI default node type from ubuntu-xenial to ubuntu-bionic.

The python3.5 binary is not provided on ubuntu-bionic and the shared
"py35" job definitions in the openstack-zuul-jobs repository have been
patched to force them to run on ubuntu-xenial [1]. We should inherit
from one of these jobs for jobs that rely on python3.5.

[1] http://lists.openstack.org/pipermail/openstack-discuss/2019-March/003746.html

Related-Bug: #1819794

Change-Id: Ie46311fa9195b8f359bfc3f61514fc7f70d78084

.zuul.yaml

@@ -63,7 +63,7 @@
 
 - job:
     name: nova-tox-functional-py35
-    parent: openstack-tox
+    parent: openstack-tox-functional-py35
     description: |
       Run tox-based functional tests for the OpenStack Nova project
       under cPython version 3.5. with Nova specific irrelevant-files list.

playbooks/legacy/nova-next/run.yaml

@@ -38,7 +38,10 @@
           cat << 'EOF' >>"/tmp/dg-local.conf"
           [[local|localrc]]
           NOVA_USE_SERVICE_TOKEN=True
-          NOVA_CONSOLE_PROXY_COMPUTE_TLS=True
+          # TODO (gmann): enable TLS console proxy once
+          # bug#1819794 is fixed. Something to take care
+          # while moving these jobs to devstack zuulv3 jobs.
+          # NOVA_CONSOLE_PROXY_COMPUTE_TLS=True
           USE_PYTHON3=True
           ENABLE_VOLUME_MULTIATTACH=True
 
@@ -56,7 +59,10 @@
           set -e
           set -x
           # tls-proxy is needed to initialize the CA and cert.
-          export ENABLED_SERVICES=tls-proxy
+          # TODO (gmann): enable TLS console proxy once
+          # bug#1819794 is fixed. Something to take care
+          # while moving these jobs to devstack zuulv3 jobs
+          # export ENABLED_SERVICES=tls-proxy
           export PYTHONUNBUFFERED=true
           # Yes we want to run Tempest.
           export DEVSTACK_GATE_TEMPEST=1