retire zammad-01.torproject.net on June 27 2022

As part of the cdr.link evaluation (#40578 (closed)), it was agreed we would setup a "hands off TPA" machine inside our account on Hetzner cloud. the machine is in a separate "non-TPA" project in Hetzner cloud, and hosted under the zammad-01.torproject.net domain name.

It should be destroyed on June 1st 2022, but a heads up should be sent earlier, obviously. The retirement checklist is basically:

1. send a notification in advance, wait a week
2. shutdown the VM, wait a week
3. destroy the VM on july 7th
4. remove it from the spreadsheet

Marked as due mid-may to send a heads up then.