Remove references to unsupported operating systems

All references to Gentoo, SUSE, Debian stretch and Centos-7  are removed.
Conditional tasks, ternary operators and variables are simplified where possible
OS specific variables files are generalised where possible

Change-Id: Ifd45cedcf98487b1a8b5531962529f0784f3065e

meta/main.yml

@@ -22,14 +22,14 @@ galaxy_info:
   platforms:
     - name: Debian
       versions:
-        - stretch
+        - buster
     - name: Ubuntu
       versions:
-        - trusty
-        - xenial
+        - bionic
+        - focal
     - name: EL
       versions:
-        - 7
+        - 8
   categories:
     - cloud
     - python

vars/redhat.yml

@@ -15,7 +15,7 @@
 
 cloudkitty_distro_packages:
   - git
-  - "{{ ansible_distribution_major_version is version('8', '<') | ternary('systemd-python', 'python3-systemd') }}"
+  - python3-systemd
   - libxml2
 
 cloudkitty_devel_distro_packages:

vars/suse.yml

@@ -1,24 +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.
-
-cloudkitty_distro_packages:
-  - git-core
-  - python-systemd
-  - libxml2
-
-cloudkitty_devel_distro_packages:
-  - pkg-config
-  - systemd-devel
-  - libxml2-devel