clean mysql better

The purge that was previously removed was actually kind of important
to burning mysql back down to a stateless zero point. Bring this back
with the addition of doing it for mariadb as well.

Change-Id: If608db8731d9ddfb2440a37387409798619b163c

lib/databases/mysql

@@ -23,7 +23,7 @@ function cleanup_database_mysql {
     if is_ubuntu; then
         # Get ruthless with mysql
         stop_service $MYSQL
-        uninstall_package mysql-common mariadb-common
+        apt_get purge -y mysql* mariadb*
         sudo rm -rf /var/lib/mysql
         sudo rm -rf /etc/mysql
         return