Use latest Trixie images for makebuildserver
...but, since vagrant went non-FLOSS (#1162) Debian stopped adding new images to Hashicorp repo
now, it appears that @eighthave might have promised to continue this work, based on this conversation: https://lists.debian.org/debian-cloud/2025/08/msg00019.html
So I used the last Debian image for "testing" from April: https://portal.cloud.hashicorp.com/vagrant/discover/debian/testing64/versions/20250426.1
$ tar -xzf vagrant.box
$ sha256sum *I've done this in Water contrib server (which had its host updated to Trixie already)
and I've successfully built Conversations HEAD for a test, with default openjdk-21
up next get openjdk-17 from Bookworm and test this case too, so this matches current recipe
/PS: @jspricke reminded us that maybe we can go back to "making our own images" like we used to do
/LE: I did not touch Docker since I can't test that