Default pre-starts to use service instead of systemctl

[drich10]

Description

The current behavior breaks rsyslog when using the docker cpi and sta…rting with systemd

• Defaulting to service until the majority, if not most, components move completely to noble+ stemcells enables the largest compatibility window

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Testing performed?

Manual testing on a docker cpi deployment. You can recreate the "broken rsyslog" state just by booting a warden stemcell with the systemd option in the docker cpi.

Checklist:

• This PR is being made against the main branch, or relevant version branch

[drich10]

/cc @alchen1218

[weili-broadcom]

/cc @chombium

[chombium]

I personally don't think that service, the fallback should be set as a default. The BOSH-Lite and Docker CPIs are full with hacks and on top of that the Docker CPI uses the Docker V1 API which is also deprecated. I guess with this PR we are only masking the root cause.

I've also started discussion on Slack in the BOSH channel to gather some experience what are the others doing in such cases.

Defaulting to service until the majority, if not most, components move completely to noble+ stemcells enables the largest compatibility window

@drich10 What do you expect to change with the noble stemcells?

[drich10]

@chombium I can appreciate that, but until that changes a breaking change in this release has made it unusable in our environments until a more general future path is chosen. I expect warden, cpis, and releases across the ecosystem will soon start tackling the broader noble compatibility, but we aren't near that being the default writ large.

[dsboulder]

Just to give context, we use BOSH Lite with the docker CPI in CI extensively to make cloud costs more affordable, locally for developing components on our own machines, and even in other cool ways. So it's gonna be pretty bad for us (and the CFF) cost and productivity-wise if we can't continue to take this shortcut.

[chombium]

LGTM!

Thanks @drich10 for the change and @dsboulder for the explanation. I know that the Bosh-Lite and Docker CPIs are full of hacks to make things work on a local machine and I've rethought the whole problem. As we don't use some advanced systemctl calls, it should be ok if we change the defaults.

Please make sure that you tests everything on "real foundations" as well where systemd runs with pid = 1, so that we don't have any regressions.