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: Ibe914d0d547b930b8167bfa475cc838df8d7ae25

meta/main.yml

@@ -20,15 +20,16 @@ galaxy_info:
   license: Apache2
   min_ansible_version: 2.2
   platforms:
+    - name: Debian
+      versions:
+        - buster
     - name: Ubuntu
       versions:
-        - xenial
+        - bionic
+        - focal
     - name: EL
       versions:
-        - 7
-    - name: opensuse
-      versions:
-        - 15
+        - 8
   categories:
     - cloud
     - python

tasks/repo_install.yml

@@ -18,7 +18,7 @@
     key: "{{ repo_centos_epel_key }}"
     state: present
   when:
-    - ansible_facts['pkg_mgr'] in ['yum', 'dnf']
+    - ansible_facts['pkg_mgr'] == 'dnf'
   register: _add_yum_keys
   until: _add_yum_keys is success
   retries: 5
@@ -34,7 +34,7 @@
     state: present
     includepkgs: 'lsyncd'
   when:
-    - ansible_facts['pkg_mgr'] in ['yum', 'dnf']
+    - ansible_facts['pkg_mgr'] == 'dnf'
   register: install_epel_repo
   until: install_epel_repo is success
   retries: 5
@@ -47,7 +47,7 @@
     baseurl: "{{ repo_centos_nginx_mirror }}"
     gpgkey: "{{ repo_centos_nginx_key }}"
   when:
-    - ansible_facts['pkg_mgr'] in ['yum', 'dnf']
+    - ansible_facts['pkg_mgr'] == 'dnf'
   register: add_nginx_repo
   until: add_nginx_repo is success
   retries: 5

vars/suse.yml

@@ -1,33 +0,0 @@
----
-# Copyright 2016, Walmart Stores, Inc.
-# Copyright 2017, SUSE LINUX GmbH.
-#
-# 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.
-
-systemd_utils_prefix: "/usr/lib/systemd"
-
-repo_nginx_pid: /var/run/nginx.pid
-
-rsyncd_service_name: rsyncd
-
-repo_server_distro_packages:
-  - lsyncd
-  - nginx
-  - openssh
-  - rsync
-  - sudo
-
-repo_lsyncd_config_file: /etc/lsyncd/lsyncd.conf
-repo_lsyncd_defaults_file: /etc/sysconfig/lsyncd
-
-repo_server_sshd: sshd