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: I5e402a943fd1d923db99f04c68c5e9510d3acc85

meta/main.yml

@@ -22,17 +22,14 @@ galaxy_info:
   platforms:
     - name: Debian
       versions:
-        - stretch
+        - buster
     - name: Ubuntu
       versions:
-        - xenial
         - bionic
+        - focal
     - name: EL
       versions:
-        - 7
-    - name: opensuse
-      versions:
-        - 15
+        - 8
   categories:
     - client
     - rsyslog

vars/suse.yml

@@ -1,35 +0,0 @@
----
-# 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.
-
-rsyslog_client_distro_packages:
-  - rsyslog
-  - logrotate
-
-rsyslog_client_distro_packages_remove:
-  - systemd-logger # conflicts with rsyslog
-
-rsyslog_client_already_handled_files: []
-
-rsyslog_client_reload: 'systemctl -q restart rsyslogd || true'
-
-rsyslog_system_logfile: /var/log/messages
-
-rsyslog_logfile_user: root
-
-rsyslog_logfile_group: root
-
-rsyslog_logfile_drop_user: root
-
-rsyslog_logfile_drop_group: root