Protobuf system test for schema tracking

[vandonr]

Motivation

Follow up on the development of this new feature, only available in Java and dotnet for now.
All languages are supposed to produce the same schema ID when extracting "from" the same proto file, so this is a perfect use case for a system test.

depends on DataDog/dd-trace-dotnet#6647
and DataDog/dd-trace-java#8403

Changes

• added a test for this use case that inspects the tags that get generated. A little bit convoluted on the span selection because we do not really control where the protobuf tags will be added
• added 2 endpoints to the java and dotnet weblogs, one doing a protobuf serialization and the other doing the deserialization.

don't be too afraid by the size of the diff, it's mostly because of the generated files: 4,118 lines for C# and 12,618 lines for java 😅

Workflow

1. ⚠️ Create your PR as draft ⚠️
2. Work on you PR until the CI passes (if something not related to your task is failing, you can ignore it)
3. Mark it as ready for review
   • Test logic is modified? -> Get a review from RFC owner. We're working on refining the codeowners file quickly.
   • Framework is modified, or non obvious usage of it -> get a review from R&P team

🚀 Once your PR is reviewed, you can merge it!

🛟 #apm-shared-testing 🛟

Reviewer checklist

• If PR title starts with [<language>], double-check that only <language> is impacted by the change
• No system-tests internal is modified. Otherwise, I have the approval from R&P team
• CI is green, or failing jobs are not related to this change (and you are 100% sure about this statement)
• A docker base image is modified?
  • the relevant build-XXX-image label is present
• A scenario is added (or removed)?
  • Get a review from R&P team

[smola]

Ideally the new endpoints should be documented at https://github.com/DataDog/system-tests/blob/main/docs/weblog/README.md

[vandonr]

github CI seems to be stuck ? But otherwise we should be good to go