Add OTLP runtime metrics system test

[link04]

Summary

Related One Pager: Sending Runtime Metrics via OTLP from dd-trace-*

• Add OTLP_RUNTIME_METRICS end-to-end scenario and test for validating that dd-trace libraries export runtime metrics via OTLP using OTel semantic convention names (dotnet.*, jvm.*, go.*, v8js.*) instead of DD-proprietary names (runtime.dotnet.*, runtime.go.*, etc.)
• Register the new scenario in CI workflow and orchestrator
• Fix parametric test_otel_metrics tests leaking runtime metrics by explicitly setting DD_RUNTIME_METRICS_ENABLED=false in test env vars

How it works

When DD_RUNTIME_METRICS_ENABLED=true + DD_METRICS_OTEL_ENABLED=true, tracers should send runtime metrics via OTLP.
The scenario routes OTLP metrics through the proxy to the agent using OTEL_EXPORTER_OTLP_METRICS_HEADERS: "dd-protocol=otlp,dd-otlp-path=agent" (same pattern as otel_integrations), then validates metric names from interfaces.agent.get_metrics() (same pattern as RUNTIME_METRICS_ENABLED).

Test coverage

One test class (Test_OtlpRuntimeMetrics) asserts:

1. All expected OTel-named metrics are present for the language under test
2. No DD-proprietary metric names appear

Expected metrics are defined per language (19 dotnet, 8 go, 13 nodejs, 18 java). All languages are missing_feature until their respective tracer PRs land.

Test plan

• OTLP_RUNTIME_METRICS scenario build from dd-trace-dotnet#8457 passes in System Test CI #6797 Dev run
• Existing RUNTIME_METRICS_ENABLED scenario unaffected
• Parametric test_otel_metrics failures fixed with DD_RUNTIME_METRICS_ENABLED=false
• CI green on system-tests

🤖 Generated with Claude Code

[github-actions]

CODEOWNERS have been resolved as:

tests/test_otlp_runtime_metrics.py                                      @DataDog/system-tests-core
.github/workflows/run-end-to-end.yml                                    @DataDog/system-tests-core
manifests/cpp.yml                                                       @DataDog/dd-trace-cpp
manifests/dotnet.yml                                                    @DataDog/apm-dotnet @DataDog/asm-dotnet
manifests/golang.yml                                                    @DataDog/dd-trace-go-guild
manifests/java.yml                                                      @DataDog/asm-java @DataDog/apm-java
manifests/nodejs.yml                                                    @DataDog/dd-trace-js
manifests/php.yml                                                       @DataDog/apm-php @DataDog/asm-php
manifests/python.yml                                                    @DataDog/apm-python @DataDog/asm-python
manifests/ruby.yml                                                      @DataDog/ruby-guild @DataDog/asm-ruby
tests/parametric/test_otel_metrics.py                                   @DataDog/system-tests-core @DataDog/apm-sdk-capabilities
utils/_context/_scenarios/__init__.py                                   @DataDog/system-tests-core
utils/scripts/ci_orchestrators/workflow_data.py                         @DataDog/system-tests-core

[datadog-prod-us1-5]

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: f74c21d | Docs | Datadog PR Page | Give us feedback!}

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