[Telemetry] Update required fields in metrics

[Anilm3]

Description

Update telemetry metrics schemas:

• Remove namespace from required fields in generate-metrics and choose relevant metric schema depending on the presence of the namespace property.
• Add namespace as valid field to metric
• Add metric schema with mandatory namespace field

As discussed with the Telemetry team, the namespace field is required either as part of individual series or as a top-level namespace, this change allows the validation of both options while ensuring the namespace is always available somewhere.

Motivation

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

[cbeauchesne]

@Anilm3 I guess it's an egg-chicken ? Do you want to merge this one before ?

[Anilm3]

@Anilm3 I guess it's an egg-chicken ? Do you want to merge this one before ?

As discussed, the tests are working locally so this isn't blocking us any longer.

[cbeauchesne]

but it may block other PR on system tests, so the sooner the CI is green, the better.