[chore] Update Kubernetes to 1.32.5 and Helm to 3.18.1; add version docs; improve code uniformity

[jvoravong]

• Kubernetes and Helm Dependency Update:
  • Updated Kubernetes (kind) version from 1.24 (maintenance support ended on July 28th, 2023) to 1.32.5 (latest)
  • Updated Helm and related dependencies in GitHub workflows from version 3.X to 3.18.1.
  • This update ensures quality of Helm-rendered examples, in other projects I noticed example render issues caused by using outdated Helm dependencies.
  • No breaking changes were identified in this project when using Kubernetes 1.32 and Helm 3.18.1.
    • But a breaking change was identified specifically for Helm 3.18.0 which causes a chart lint bug and maybe a Helm install/upgrade bug in the opentelemetry-kube-stack chart (CC: @jaronoff97).
    • Github workflow run example
    • "error converting YAML to JSON: yaml: line X: mapping values are not allowed in this context" in charts/opentelemetry-kube-stack/examples/prometheus-otel/values.yaml.
    • The fix is already out, just use Helm 3.18.1 which is currently latest.
• Documentation Enhancement:
  • Documented versions Kubernetes and Helm versions used to maintain this project in README.md. This is important for customers and really should be a matrix like document that grows over time, keeping it simple for now and just adding a couple static doc lines.
• Code Cleanup:
  • Improved uniformity across related areas for better consistency and maintainability.

[TylerHelmuth]

I like that before we had confidence when telling customers a helm minimum version for each chart, since not everyone is using the latest helm version. A couple thoughts:

1. I like rendering the examples with the latest helm
2. I like testing with our minimum supported version of k8s and helm. We can also add testing for the latest versions. This is what the operator repo does.

[jvoravong]

@TylerHelmuth great thoughts. I can update testing workflows to use a matrix input to test both oldest and latest supported versions for Kubernetes and Helm. I'll add that shortly.

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