Use generic vars file for ubuntu

These vars work for both Xenial and Bionic

Change-Id: I905c13066e49cbbce232de2fc04f0977e2548bb8

vars/ubuntu-18.04.yml

@@ -1,31 +0,0 @@
----
-# Copyright 2018, VEXXHOST, Inc.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-## APT Cache options
-cache_timeout: 600
-
-tempest_distro_packages:
-  - git-core
-  - libpq-dev
-  - python-glanceclient
-  - python-keystoneclient
-  - python-neutronclient
-  - python-novaclient
-  - rsync
-
-tempest_requires_pip_packages:
-  - shade # ubuntu xenial provides a rather old shade library. We need >= 1.9.0 for Rocky
-  - virtualenv
-  - setuptools # Ubuntu's setuptools package does not contain pkg-resources and that's causing troubles