refactor: Refactor child_process instrumentation to use tracing channel instead of Shim

[amychisholm03]

Description

This PR converts the child_process exec/execFile instrumentation from Shim-based monkeypatching to utilize Node's native tracing channel API. It creates one tracingChannel per method and monkey patches each exec/execFile function once per process. It keeps the nested Callback: <name> segment if a callback was provided.

How to Test

npm run unit
npm run integration

Related Issues

Closes #4223

[codecov]

Codecov Report

❌ Patch coverage is 97.40260% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.44%. Comparing base (6bf954b) to head (c853544).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/subscribers/tc-base.js	96.99%	4 Missing ⚠️
lib/subscribers/child_process/exec.js	97.10%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4212      +/-   ##
==========================================
- Coverage   97.52%   97.44%   -0.08%     
==========================================
  Files         522      525       +3     
  Lines       62959    63139     +180     
  Branches        1        1              
==========================================
+ Hits        61400    61526     +126     
- Misses       1559     1613      +54     

Flag	Coverage Δ
integration-tests-cjs-22.x	73.69% <97.40%> (+0.08%)	⬆️
integration-tests-cjs-24.x	74.28% <97.40%> (+0.08%)	⬆️
integration-tests-cjs-26.x	74.28% <97.40%> (+0.08%)	⬆️
integration-tests-esm-22.x	54.66% <82.25%> (+0.09%)	⬆️
integration-tests-esm-24.x	55.95% <82.25%> (+0.08%)	⬆️
integration-tests-esm-26.x	55.95% <82.25%> (+0.08%)	⬆️
unit-tests-22.x	89.09% <83.11%> (-0.03%)	⬇️
unit-tests-24.x	89.04% <83.11%> (-0.03%)	⬇️
unit-tests-26.x	89.04% <83.11%> (-0.03%)	⬇️
versioned-tests-22.x	97.44% <97.40%> (-0.08%)	⬇️
versioned-tests-24.x	97.44% <97.40%> (-0.08%)	⬇️
versioned-tests-26.x	97.44% <97.40%> (-0.08%)	⬇️

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[jsumners-nr]

Looking good, but I think we can improve a few things.

[bizob2828]

I haven't studied this but we should keep the instrumentation separate from the subscribers of instrumentation. I know they are in separate classes but the subscribers should live in lib/subscribers. I know this is the first but we should be creating abstractions like the orchestrion and native diagnostics channel based instrumentation so it can be reused for future core node library subscribers

[bizob2828]

a few more comments. this is a good start but we probably want to study the abstracted design more as we add more core node.js subscribers and instrumentation that runs in tracing channels