parametric: Define docker cmd in Dockerfile

[cbeauchesne]

Motivation

Changes

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:

utils/_context/_scenarios/parametric.py                                 @DataDog/system-tests-core
utils/build/docker/cpp/parametric/Dockerfile                            @DataDog/dd-trace-cpp @DataDog/system-tests-core
utils/build/docker/dotnet/parametric/Dockerfile                         @DataDog/apm-dotnet @DataDog/asm-dotnet @DataDog/system-tests-core
utils/build/docker/golang/parametric/Dockerfile                         @DataDog/dd-trace-go-guild @DataDog/system-tests-core
utils/build/docker/java/parametric/Dockerfile                           @DataDog/apm-java @DataDog/asm-java @DataDog/system-tests-core
utils/build/docker/nodejs/parametric/Dockerfile                         @DataDog/dd-trace-js @DataDog/system-tests-core
utils/build/docker/php/parametric/Dockerfile                            @DataDog/apm-php @DataDog/system-tests-core
utils/build/docker/python/parametric/Dockerfile                         @DataDog/apm-python @DataDog/asm-python @DataDog/system-tests-core
utils/build/docker/ruby/parametric/Dockerfile                           @DataDog/ruby-guild @DataDog/asm-ruby @DataDog/system-tests-core
utils/build/docker/rust/parametric/Dockerfile                           @DataDog/apm-rust @DataDog/system-tests-core
utils/docker_fixtures/_test_client.py                                   @DataDog/system-tests-core