lxd-to-incus: query systemd instead of assuming service file path

[adamcstephens]

systemd supports multiple paths, so rely on its detection logic instead of checking a specific path.

[stgraber]

Commit isn't signed-off, please make sure the commit message includes the Signed-off-by: Firstname Lastname <email> line.

[adamcstephens]

Fixed.

[stgraber]

 Checking for oneline assign & test...
cmd/lxd-to-incus/targets.go:28:	if _, err := subprocess.RunCommand("systemctl", "list-unit-files", "incus.service"); err != nil {

Our code style doesn't allow for one-line define+check syntax, so you'll need to update that to be two lines instead.

[adamcstephens]

Fixed. I wish github would allow workflows on a PR that has already been approved to run them. :(

I missed the 0.2 release so we'll carry this as a patch for NixOS.

[stgraber]

Yeah, we have the setting on Github Actions to require an initial approval for a new contributor which is fine, except that Github apparently requires it for every change in that initial PR...