Add new test_sample_rate_function

[LotharSee]

Description

Add a new test test_sample_rate_function which checks that weblog takes the exact same sampling decision as the one precomputed in an auxiliary .csv file.

This test is broader and stricter than the previous tests test_sampling_decision, test_sampling_decision_added and test_sampling_decision_added (if any of them fail, the new one would fail too). In a later PR, I'll propose to consolidate it all.

Motivation

The purpose of this approach is to use a portable language agnostic set of (trace_id, sampling_rate, sampling_decision) to test the implementation of the sampling function. The given CSV can be copied to be sure in libraries' unit tests. I plan on using it on to test our backend implementation too.
The CSV is meant to include cases for "tricky" values (ex: small, large, at the edge of 2^63) which would who typically fail if the function were badly implemented (ex: offset by one, doing a 2^63 modulo instead of 2^64).

Workflow

1. ⚠️⚠️ Create your PR as draft
2. Follow the style guidelines of this project (See how to easily lint the code)
3. Work on you PR until the CI passes (if something not related to your task is failing, you can ignore it)
4. Mark it as ready for review

Once your PR is reviewed, you can merge it! ❤️

Reviewer checklist

• Check what scenarios are modified. If needed, add the relevant label (run-parametric-scenario, run-profiling-scenario...). If this PR modifies any system-tests internal, then add the run-all-scenarios label (more info).
• CI is green
  • If not, failing jobs are not related to this change (and you are 100% sure about this statement)
• if any of build-some-image label is present
  1. is the image labl have been updated ?
  2. just before merging, locally build and push the image to hub.docker.com
• if a scenario is added (or removed), add (or remove) it in system-test-dasboard nightly