python_lambda: allow for library target branches and detect arch in install script

[florentinl]

APPSEC-60129

Motivation

• To be able to run tests locally on an arm64 laptop without having to modify the install_datadog_lambda.sh script
• To use the library target branch feature, for testing

Changes

• Parse the current architecture to fetch the correct artifact
• Parse library target branches for python_lambda as well

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:

.github/actions/get_target_branch/action.yaml                           @DataDog/system-tests-core
utils/build/docker/python_lambda/install_datadog_lambda.sh              @DataDog/apm-python @DataDog/asm-python @DataDog/system-tests-core
utils/scripts/load-binary.sh                                            @DataDog/system-tests-core