TSH-18197 - Propagate trace context on websocket upgrade request (copy #8739)

[mergify]

TSH-18197

Router does not currently propagate the trace context for websocket connections. This is problematic and prevents important diagnostic and observability capabilities for Router subscriptions.

This simple PR adds propagation to the http request that is used to upgrade to websockets.

I have system tested this with Netflix DGS/Spring Boot based subgraphs with subscriptions instrumented with Datadog's dd-trace-java APM instrumentation library, and verified spans emanated from the subgraph for the subscription are now showing up and are associated with the trace.

---

Checklist

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

• PR description explains the motivation for the change and relevant context for reviewing
• PR description links appropriate GitHub/Jira tickets (creating when necessary)
• Changeset is included for user-facing changes
• Changes are compatible¹
• Documentation² completed
• Performance impact assessed and acceptable
• Metrics and logs are added³ and documented
• Tests added and passing⁴
  • Unit tests
  • Integration tests
  • Manual tests, as necessary

Exceptions

Note any exceptions here

Notes

---

This is an automatic copy of pull request #8739 done by [Mergify](https://mergify.com).

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. A lot of (if not most) features benefit from built-in observability and debug-level logs. Please read this guidance on metrics best-practices. ↩

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

[apollo-cla]

@mergify[bot]: Thank you for submitting a pull request! Before we can merge it, you'll need to sign the Apollo Contributor License Agreement here: https://contribute.apollographql.com/

[apollo-librarian]

✅ Docs preview has no changes

The preview was not built because there were no changes.

Build ID: 73d12e7a2fae343f8ee470b9
Build Logs: View logs

[aaronArinder]

@theJC: tests passing locally, hopefully in circle too; the code's in a place for a business logic review now, and I plan on doing that tomorrow

[bnjjj]

@aaronArinder @theJC I added a comment here but that can be done in a follow up PR if needed