.github/workflows: integrate APM E2E tests in Github Actions CI

[lambrospetrou]

What does this PR do?

This PR enables the APM end-to-end (E2E) tests in Github Actions CI.

At the moment, the default test is enabled for all variants, but the Single Spans test is only implemented for the chi variant. All other variants will still run the jobs, but are skipped (in system-tests terms they are expectedly failing).

Once we verify that this works well, we can implement the rest variants too, in follow-up PRs.

Examples of successful jobs:

• chi: https://github.com/DataDog/dd-trace-go/actions/runs/4366904885/jobs/7651749363
  • Single Spans test runs and passes.
• echo: https://github.com/DataDog/dd-trace-go/actions/runs/4366904885/jobs/7651749157
  • Single Spans test is expectedly skipped.

Motivation

We had several incidents with features not working correctly due to incorrect assumptions, and bugs, in some component of the whole APM tracing pipeline (tracer, agent, backend).

We want to enable end-to-end tests for key use-cases to avoid regressions in the future.
See ATI-2419 for more details.

Describe how to test/QA your changes

Reviewer's Checklist

• If known, an appropriate milestone has been selected; otherwise the Triage milestone is set.
• Changed code has unit tests for its functionality.
• If this interacts with the agent in a new way, a system test has been added.

[pr-commenter]

Benchmarks

Comparing candidate commit c2b671b in PR branch lambros.petrou/integrate-e2e-system-tests with baseline commit 5b41544 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 6 cases.

[knusbaum]

LGTM