[signal] Fix context propagation in signal server

[4thel00z]

• Use guardian pattern to reduce control flow depth
• Fixed variable & package name clash
• Propagate ctx in Server.Send
• Enable graceful shutdown in Server.ConnectStream, by honoring <-stream.Context().Done()

Describe your changes

Issue ticket number and link

Checklist

• Is it a bug fix
• Is a typo/documentation fix
• Is a feature enhancement
• It is a refactor
• Created tests that fail without the change (if possible)
• Extended the README / documentation, if necessary

[CLAassistant]

All committers have signed the CLA.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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[mlsmaycon]

Thanks, @4thel00z, for the contribution. We will review it soon

[4thel00z]

No problem, happy to remove any merge blockers.

[4thel00z]

I'm seeing that the amd64 postgres benchmark is failing also for other PRs.
Do you want me to address that in another PR ? @mlsmaycon

[pascal-fischer]

Hi @4thel00z, thanks for the PR. I had a look a few days ago and the code looks good. I do need to test it, which I didn't get around to yet. I think there was a reason for the context.Background() but I will confirm once I tested.

Regarding the benchmarks, they sometimes fail if they are defined too strictly and the runner has a particularly bad day. You don't need to adjust those. A simple re-run of the test will help, and we will adjust them later if needed.

[pascal-fischer]

Ok the context.Background() is not required anymore. That's a leftover from code that is long gone. The looks good, I tested and everything is fine.