[golang] Accept env var format for telemetry keys

[mtoffl01]

Motivation

Upcoming changes to dd-trace-go will report configuration telemetry as env-var keys.
Follow-up to: #5709

Changes

Adds support for legacy telemetry reporting format and new, env var reporting format for golang

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

• 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
• 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

[github-actions]

CODEOWNERS have been resolved as:

tests/parametric/test_telemetry.py                                      @DataDog/system-tests-core @DataDog/apm-sdk-capabilities