refactor(contrib/confluent-kafka-go/kafka): extract tracing code

[darccio]

What does this PR do?

Refactoring tracing code for contrib/confluent-kafka-go/kafka to have an internal implementation usable by Orchestrion.

Reviewer's Checklist

• Changed code has unit tests for its functionality at or near 100% coverage.
• System-Tests covering this feature have been added and enabled with the va.b.c-dev version tag.
• There is a benchmark for any new code, or changes to existing code.
• If this interacts with the agent in a new way, a system test has been added.
• Add an appropriate team label so this PR gets put in the right place for the release notes.
• Non-trivial go.mod changes, e.g. adding new modules, are reviewed by @DataDog/dd-trace-go-guild.

Unsure? Have a question? Request a review!

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-10-02 09:34:54

Comparing candidate commit 7bd514a in PR branch dario.castane/APPSEC-53286/refactor-tracing with baseline commit 82f0b8e in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 59 metrics, 0 unstable metrics.

[darccio]

Closed in favour of #2907