Currently:
- We maintain a list of db hosts in modules/install_server/files/autoinstall/netboot.cfg
- This case entry uses the no-srv-format.cfg partman recipe, which fails, and requires human input. This is used as a safety feature.
- To reimage a host you create a more specific case with no partman recipe, which then causes the installer to block on human input.

In the near future we'll have a fixed no-srv-format partman recipe. This means that db hosts will successfully reimage, even if it's not intended.

Proposal:
- Drop the case entry from netboot.cfg. This will cause all db hosts to block on human input by default.
- To reimage a host you create a specific case with the (fixed) no-srv-format partman recipe, which will make the installer run to completion.

Benefits:
- We retain the same safety level - a db host can never lose data without explicit human interaction.
- We do not have to maintain the pattern that matches all the db hosts.

Cons:
- It's still technically possible for someone to connect to the console and manually format /srv etc.
  - But, as such manual interaction will no longer be part of the normal workflow, this doesn't seem very likely (to me).