Add testcase for k8s parsing

[SylvainJuge]

Found while investigating some customer issues with the Java agent elastic/apm-agent-java#3418.

The parsing of the container ID used to include the containerd- prefix, which is not something that is expected. As a consequence including it in the shared tests helps to prevent this issue from happening with other agents.

I have also seen this in practice in the data collected on ES clusters in Elastic Cloud, while it has been reported when using the "gardener" k8s tool, this might also apply to other similar tools.

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• May the instrumentation collect sensitive information, such as secrets or PII (ex. in headers)?
  • n/a: it just updates an automated test data
• Create PR as draft
• Approval by at least one other agent
• Mark as Ready for Review (automatically requests reviews from all agents and PM via CODEOWNERS)
  • Remove PM from reviewers if impact on product is negligible
  • Remove agents from reviewers if the change is not relevant for them
• Approved by at least 2 agents + PM (if relevant)
• Merge after 7 days passed without objections
  To auto-merge the PR, add /schedule YYYY-MM-DD to the PR description.
• Create implementation issues through the meta issue template (this will automate issue creation for individual agents) will be implicit through the spec sync PRs on each impacted agent.

[trentm]

the "gardener" k8s tool

https://gardener.cloud/ apparently.

[Mpdreamz]

LGTM