[Utility] Optimize usage of HTTP client for performing relays

[adshmh]

Objective

Optimize usage of HTTP client, e.g. for connection reuse, by the servicer. This can be very important depending on the volume of relays a servicer is expected to handle.

Origin Document

Part of work on #754

Starting point, from #803:

and

Goals

• Investigate settings for optimal performance of HTTP clients (and the underlying Transport in the standard HTTP library of GOLANG): examples include Connection Reuse, Connection Pools, etc.
• Implement the requied optimization in the servicer when serving the relay.

Deliverable

• Documentation of the expected volume of relays a servicer should be able to handle, possibly defined as multiple SLAs.
• Documentation of the optimizations deemed necessary to achieve the expected performance
• Updating the code of servicer and other related components.

Non-goals / Non-deliverables

General issue deliverables

• Update any relevant local/global README(s)
• Update relevant source code tree explanations
• Add or update any relevant or supporting mermaid diagrams

Testing Methodology

• Task specific tests or benchmarks: make ...
• New tests or benchmarks: make ...
• All tests: make test_all
• LocalNet: verify a LocalNet is still functioning correctly by following the instructions at docs/development/README.md
• k8s LocalNet: verify a k8s LocalNet is still functioning correctly by following the instructions here

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Creator: @adshmh
Co-Owners: @Olshansk

[Olshansk]

@adshmh NIT (no action but for future reference): If there is a screenshot you can take of the code, PR or documentation as part of the origin document, I've found it really helps both the owner (in case a lot of time goes by), myself and others.

For this one, I could find anything perfect, but this from #778 is a good starting point to look at the code

[adshmh]

@adshmh NIT (no action but for future reference): If there is a screenshot you can take of the code, PR or documentation as part of the origin document, I've found it really helps both the owner (in case a lot of time goes by), myself and others.

For this one, I could find anything perfect, but this from #778 is a good starting point to look at the code

Thank you for the suggestion. I updated the Issue description with 2 screenshots which focus on the specific area this issue is about.