[dotnet@maximo/otlp-runtime-metrics] Enable OTLP runtime metrics test for .NET

[link04]

Summary

• Enable Test_OtlpRuntimeMetrics for .NET v3.43.0 in the dotnet manifest
• Depends on dd-trace-dotnet#8457 being merged first
• Depends on system-tests#6715 being merged first (adds the scenario and test)

Test plan

• dd-trace-dotnet#8457 merged
• system-tests#6715 merged
• CI green with .NET OTLP runtime metrics test passing

🤖 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-datadog-prod-us1]

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

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