Resolves issue-16844 - systemd notify by default

[drawks]

• updates consul.service systemd service unit to use Type=notify to resolve issue systemd unit does not use systemd notify, documentation doesn't provide example of using systemd notify #16844

Description

To resolve issue #16844 and switch packaged systemd unit to use systemd's notify mechanism by default.

Testing & Reproduction steps

See #16844 where the steps to reproduce the current and updated behavior are documented

Links

#2121
31a310f
https://developer.hashicorp.com/consul/docs/agent#understanding-the-agent-startup-output
https://developer.hashicorp.com/consul/tutorials/production-deploy/deployment-guide#configure-the-consul-process

PR Checklist

• updated test coverage
• external facing docs updated
• not a security concern

[github-actions]

This pull request has been automatically flagged for inactivity because it has not been acted upon in the last 60 days. It will be closed if no new activity occurs in the next 30 days. Please feel free to re-open to resurrect the change if you feel this has happened by mistake. Thank you for your contributions.

[drawks]

Any updates on this PR? It is a very minor change and shouldn't require any updated tests.

@alvin-huang @sarahethompson I see you got assigned as reviewers

[drawks]

I've rebased this since it hasn't been looked at in a while. Tests are passing except for the one requiring a label, which needs a maintainer to add either a no-backport or backport to current supported versions (this change is super low risk and should be totally non-disruptive in 99% of cases). The changelog update check doesn't give any advice as to the expected changelog update style/semantics. I'd be happy to make whatever changes are needed to get this merged.

On a human note it feels pretty ridiculous that hashicorp sends me all sorts of "core contributor" swag in the mail but can't be bothered to even comment on this TINY pr which I've submitted.

[loshz]

Hey @drawks, thanks for fixing this issue and sorry for the delayed response. You are right in that the systemd unit should contain this, as our docs clearly state the requirement.

I'm happy to accept this if you wouldn't mind adding a changelog. The file should be .changelog/16845.txt:
```release-note:improvement
systemd: set service type to notify.
```

[drawks]

@loshz thanks for the response, I've just squashed the changelog update as requested into my branch. I'm looking forward to systemd being able to order my services correctly (without any local gyrations) :)

[loshz]

@loshz thanks for the response, I've just squashed the changelog update as requested into my branch. I'm looking forward to systemd being able to order my services correctly (without any local gyrations) :)

Apologies, but the changlelog has to include the back ticks (for reason's unknown to me):

```release-note:improvement
systemd: set service type to notify.
```

[drawks]

@loshz ha! I've just squshed in a fix for that

[loshz]

Thanks again, @drawks. I can help with the backports if they don't automerge.