Instrument coprocessor request with http_request span

[theJC]

Instrument coprocessor request with http_request span, to be consistent in observability to subgraph http requests.

Code basically copy/pasted from apollo-router/src/services/http/service.rs

Provides Apollo's customers insight into latency that may be introduced over the network stack when communicating with coprocessor.

Fixes #6739

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Checklist

Complete the checklist (and note appropriate exceptions) before the PR is marked ready-for-review.

• Changes are compatible¹
• Documentation² completed
• Performance impact assessed and acceptable
• Tests added and passing³
  • Unit Tests
  • Integration Tests
  • Manual Tests

Manual test:

Exceptions

Note any exceptions here

Notes

Footnotes

1. It may be appropriate to bring upcoming changes to the attention of other (impacted) groups. Please endeavour to do this before seeking PR approval. The mechanism for doing this will vary considerably, so use your judgement as to how and when to do this. ↩

2. Configuration is an important part of many changes. Where applicable please try to document configuration examples. ↩

3. Tick whichever testing boxes are applicable. If you are adding Manual Tests, please document the manual testing (extensively) in the Exceptions. ↩

[svc-apollo-docs]

✅ Docs preview has no changes

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Build ID: 28bbf21931d152e6d0d74026

[theJC]

@bnjjj -- Any chance I can ask for a couple minutes of your time for a review (or point someone to me or me to someone that would be the best person to take a look at this contribution)

Thank you in advance!

[BrynCooke]

If we use the semantic conventions for the span attributes then I think we can merge this.

Ideally we would use the existing HttpClient code for coprocessors but this is a bigger change that would be backwards compatible with what we have here.

[BrynCooke]

Let's use the Otel semantic conventions here: https://opentelemetry.io/docs/specs/semconv/http/http-spans/#http-client

[theJC]

Updated to include required attributes for http-client spans

[theJC]

Zipkin view with semconv in place:

[BrynCooke]

@theJC I will bring this PR into the router repo so that we can have the CI tests run. Any further changes can be made from there.

[theJC]

@BrynCooke -- Bringing the branch/MR into the Router repo is not something I can do for you, is it?

[BrynCooke]

I'm ooo for the next couple of days. But I'll create the new pr when I am next at my computer.

[BrynCooke]

#6856