Add dotnet supported cases _dd.svc_src span tag

[NachoEchevarria]

Motivation

Changes

This PR enables the .NET tracer system tests for the _dd.svc_src span tag, which indicates the source of a service name override (e.g., "m" for manually set values, or integration-defined values for database spans).

These tests were defined here: #6438

Manual scenario is not yet supported.

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:

manifests/dotnet.yml                                                    @DataDog/apm-dotnet @DataDog/asm-dotnet
utils/build/docker/dotnet/weblog/Dependencies/Sql.cs                    @DataDog/apm-dotnet @DataDog/asm-dotnet @DataDog/system-tests-core

[datadog-official]

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

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