What does this PR do?

This PR continues the groundwork for Kubernetes hints integration tests. The next and last episode of this PR-series can be seen here 2ea1f2f. Again these were split up because I want to keep each PR around 500 lines.

Key changes in this PR:

1. Transition Kubernetes integration tests to an "adapter" pattern:

   • Refactors Kubernetes integration tests to follow a more modular and reusable adapter pattern.
   • Introduces k8sTestStep functions that encapsulate individual test steps for clarity and flexibility.
   • Simplifies the test flow by eliminating repetitive code and leveraging reusable functions like k8sStepCreateNamespace, k8sStepDeployKustomize, and k8sStepRunInnerTests.
   • Improves readability and maintainability.

2. Align all kubernetes integration tests:

   • All kubernetes integration tests got an empty for now skipReason.
   • All kubernetes integration tests check for schedulable k8s nodes and got more deterministic in the number of agent pods expected to be running.

Why is it important?

The adapter pattern for Kubernetes integration tests enhances readability, maintainability, making it easier to add or modify test cases.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] I have made corresponding changes to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• [ ] I have added an entry in ./changelog/fragments using the changelog tool
• I have added an integration test or an E2E test

Disruptive User Impact

• None expected. The changes affect only the internal kubernetes integration tests without altering user-facing configurations or behaviours.

How to test this PR locally

mage integration:auth
PLATFORMS=linux/arm64 EXTERNAL=true SNAPSHOT=true PACKAGES=docker mage -v package 
INSTANCE_PROVISIONER=kind STACK_PROVISIONER=stateful K8S_VERSION=v1.31.1 SNAPSHOT=true mage integration:kubernetes

Related issues

• Relates Include hints autodiscovery configuration inside integration tests for k8s #5660

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  This is an automatic backport of pull request [k8s]: transition integration tests to adapter pattern #6277 done by Mergify.