fix(golang): trace non-standard HTTP methods in Chi weblog

[marcotc]

Motivation

Chi rejects non-standard HTTP methods before the route middleware runs.
As a result, test that exercise non-standard HTTP methods don't execute correctly.

This supports APMAPI-2127 and the server semantic-convention behavior in DataDog/dd-trace-go#5242.

Changes

Allow the non-standard HTTP method used by semantic-convention coverage to reach route tracing middleware.
We can't simply restore a global middleware, since that breaks AppSec.

We use PROPFIND because that's the "non-standard HTTP method" we use today.

Validation:

• ./format.sh
• git diff --check

Local image build and focused scenario validation were blocked because the sandbox denied Docker Hub access while fetching golang:1.26-alpine.

Workflow

1. ⚠️ Create your PR as draft ⚠️
2. Work on you PR until the CI passes
3. Mark it as ready for review
   • Test logic is modified? -> Get a review from RFC owner.
   • Framework is modified, or non obvious usage of it -> get a review from R&P team

🚀 Once your PR is reviewed and the CI green, you can merge it!

🛟 #apm-shared-testing 🛟

Reviewer checklist

• Anything but tests/ or manifests/ is modified ? I have the approval from R&P team
• A docker base image is modified?
  • the relevant build-XXX-image label is present
• A scenario is added, removed or renamed?
  • Get a review from R&P team

[github-actions]

CODEOWNERS have been resolved as:

utils/build/docker/golang/app/chi/main.go                               @DataDog/system-tests-reviewers

[datadog-datadog-prod-us1-2]

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

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[zacharycmontoya]

I don't see risk in merging this as-is, but it would be better if we merged this with an additional change to unskip a Chi weblog test case