Dropping 32-bit ISOs from Xubuntu 19.04 and Forward

[Adam Conrad]

On Sun, Dec 02, 2018 at 08:23:15AM -0500, Sean Davis wrote:
> 
> Please let me know what additional steps are needed to discontinue building
> this ISO.

I've removed it both from the ISO tracker and the cdimage build infra,
it should be gone for good.

... Adam