See team#41364

Stumbled upon this while trying to figure out whether I need staging
for spec.tpo and how I would go around doing it (team#41348).

when migrating instances across clusters, the persistent qemu disk
identifier changes, which throws off the grub-pc package upgrade process
which relies on those identifiers never changing

See gitlab#145 and gitlab#23.

this replaces the "-h db.torproject.org" pattern, which no longer works
on bookworm, to "-H ldap://db.torproject.org", which does

Those are typically trashed at the end and overlap with the following
dsa-check-packages.

I've done a bunch of upgrades without screen on because of this: I
would return to step 4 and just follow it, not copy-pasting from the
previous step. This is actually how it's done in the other step, so
this also happens to be more coherent.