Add Datadog code coverage upload

[ManuelPalenzuelaDD]

What does this PR do?

We're migrating Datadog repos from Codecov to Datadog Code Coverage for tracking test coverage. This PR adds a Datadog coverage upload alongside the existing Codecov upload so we can run both systems in parallel and verify parity before switching over.

Changes

• Makefile: Added datadog-ci coverage upload after the existing Codecov upload in the coverage target. Uses apk add nodejs npm && npx @datadog/datadog-ci since the CI image is Alpine/musl-based (no glibc binary available).
• .gitlab/build-and-test-fast.yml: Fetches DD_API_KEY from Vault (kv/k8s/gitlab-runner/nginx-datadog/datadoghq-api-key) and passes it to make coverage.

Why are we doing this?

As part of a company-wide effort, we're consolidating code coverage reporting into Datadog's own Code Coverage product. This gives us:

• Coverage data integrated directly into Datadog CI Visibility
• PR gates and coverage checks natively in Datadog
• No dependency on a third-party service (Codecov) for coverage reporting

Notes

• The existing Codecov upload is unchanged
• The Datadog upload uses || true so it cannot fail the build
• Requires kv/k8s/gitlab-runner/nginx-datadog/datadoghq-api-key in Vault (Paweł is adding this)

No action needed from reviewers beyond normal review

This is a low-risk, additive change.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 68.85%. Comparing base (a24070f) to head (1d97316).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #339   +/-   ##
=======================================
  Coverage   68.85%   68.85%           
=======================================
  Files          56       56           
  Lines        7471     7471           
  Branches     1058     1058           
=======================================
  Hits         5144     5144           
  Misses       1820     1820           
  Partials      507      507           

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[datadog-datadog-prod-us1]

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 67.61%

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 1d97316 | Docs | Datadog PR Page | Was this helpful? React with 👍/👎 or give us feedback!}