unattended-installer: Drop unjustified use of HashTable
unattended-installer: Drop unjustified use of HashTable

HashTables are for keeping mapping from one entity to another, not for
keeping a list of items. Lets use arrays and at the same time avoid
warning from valac about use of deprecated GLib.Hashtable.add().

vbenes/gnome-boxes,vbenes/gnome-boxes