fwupd: Delete the file from the cache when installed

It's super-unlikely the user will ever use this archive again.
1 job for <span class="ref-name">wip/hughsie/fwupd-cache</span> in 15 minutes and 42 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #243446
build-gnome-software

00:15:42