Per advice of tech-ctte, `dh_installtmpfiles` should:
* Default to adding a dependency on:
`systemd-standalone-tmpfiles | systemd | systemd-tmpfiles`
* There should be a way to opt-out. Pseudo-essential + essential
must not have this dependencies. Other packages may want to opt-out
for other reasons.
Note: Opt-out should often mean translate the Dependency to a
Recommends or Suggests.
* The snippet can stay as it is. It will work correctly either way.