Upgrade: Make removal list distribution-specific

When trying to execute an upgrade the removal fails
if packages in the list are included that cannot be
found in one of the repositories configured.

This patch endeavours to only remove packages that
will be found.

Change-Id: I67cc225b25fca005cdba3bf67793b4f23d6ae82a

tasks/galera_upgrade_pre.yml

@@ -79,11 +79,7 @@
     name: "{{ item }}"
     state: absent
   with_items:
-    - "mariadb-galera-server*"
-    - "mariadb-server*"
-    - MariaDB-Galera-server
-    - MariaDB-server
-    - mysql-common
+    - "{{ galera_server_upgrade_packages_remove }}"
   tags:
     - galera-upgrade
     - galera-apt-packages

vars/redhat-7.yml

@@ -39,6 +39,11 @@ galera_server_mariadb_distro_packages:
   - rsync
   - socat
 
+# The packages to uninstall during an upgrade from a previous version
+galera_server_upgrade_packages_remove:
+  - MariaDB-Galera-server
+  - MariaDB-server
+
 _galera_repo_url: "http://yum.mariadb.org/10.1/centos/7/x86_64"
 galera_repo:
   name: MariaDB

vars/ubuntu-16.04.yml

@@ -58,6 +58,11 @@ galera_server_mariadb_distro_packages:
   - rsync
   - socat
 
+# The packages to uninstall during an upgrade from a previous version
+galera_server_upgrade_packages_remove:
+  - mariadb-server
+  - mysql-common
+
 galera_debconf_items:
   - question: "mysql-server/root_password"
     name: "{{ galera_mariadb_server_package }}"