Changes the vm-informant's postgres connection string's dbname from
"neondb" (which sometimes doesn't exist) to "postgres" (which
_hopefully_ should exist more often?).
Currently there are a handful of VMs in prod that aren't working with
autoscaling because they don't have the "neondb" database.
The vm-informant doesn't require any database in particular; it's just
connecting as `cloud_admin` to be able to adjust the file cache
settings.
Re-enable cgroup shenanigans in VMs, with some special care taken to
make sure that our version of cgroup-tools supports cgroup v2 (debian
bullseye does not, and probably won't because it requires a breaking
change in libcgroup).
This involves manually building libcgroup / cgroup-tools from source,
then copying the output into the final build stage.
We originally considered pulling the package from debian's testing repo
(which is up-to-date), but decided against it. Refer to the PR for more
details.
Prior work, for reference:
* 2153d2e0 - Run compute_ctl in a cgroup in VMs
* 1360361f - Fix missing VM cgconfig.conf
* 8dae8799 - Disable VM cgroup shenanigans
