Refactor keepalive-related fields in confighttp

[mx-psi]

Description

This draft PR shows how we could reorganize legacy fields.

I am not convinced that we should do this because it changes quite a few options and it can be disruptive to end users, specially given that, because of the declarative configuration, this may go in a different direction upstream and we want to stay aligned if possible.

Link to tracking issue

Fixes #14020

[mx-psi]

I am not convinced that we should do this because it changes quite a few options and it can be disruptive to end users, specially given that, because of the declarative configuration, this may go in a different direction upstream and we want to stay aligned if possible.

@codeboten Is this fear unfounded? Searching I could find open-telemetry/opentelemetry-specification/issues/4440 which does mention keepalives explicitly, but I don't know how to think about this

[codspeed-hq]

CodSpeed Performance Report

Merging #14203 will improve performances by ×290

_{Comparing mx-psi:mx-psi/poc-confighttp-keepalive (227d319) with main (10f119c)¹}

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

Summary

⚡ 1 improvement
✅ 114 untouched
⏩ 1 skipped²

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	BenchmarkPersistentQueue	206,515 ns	721 ns	×290

Footnotes

1. No successful run was found on main (1578cf8) during the generation of this report, so 10f119c was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

2. 1 benchmark was skipped, so the baseline result was used instead. If it was deleted from the codebase, click here and archive it to remove it from the performance reports. ↩

[codspeed-hq]

Unable to generate the flame graphs

The performance report has correctly been generated, but there was an internal error while generating the flame graphs for this run. We're working on fixing the issue. Feel free to contact us on Discord or at [email protected] if the issue persists.

[dmitryax]

I'm supportive of this approach. I think we can finalize the migration before marking confighttp 1.0