ci: test across several k8s versions

[pmalek]

What this PR does / why we need it:

This PR:

• adds testing on multiple Kubernetes versions using the added .github/supported_k8s_node_images.yaml
• removes the namespace field validation on KonnectConfigurationDataPlaneGroup networkRef field
  • using CEL reserved keywords is only available in Kubernetes 1.32+ (introduced in chore: bump DefaultKubeBinaryVersion to 1.32, make 1.32 CEL changes, fix int tests to handle 1 version off API deprecation, and fix prerelease-lifecycle-gen for # of APIs kubernetes/kubernetes#126977). This validation can be re-introduced when 1.32 becomes the oldest supported version.
• adjusts the ExpectedErrorMessage in KonnectExtension test
  • NOTE: Kubernetes 1.32 changed the validation error for values exceeding the maximum length.
    It used to be:
    Too long: may not be longer than 63
    In 1.32+ it is:
    Too long: may not be more than 63 bytes

Which issue this PR fixes

Fixes #393

Special notes for your reviewer:

A follow up PR will release 1.3.2

PR Readiness Checklist:

Complete these before marking the PR as ready to review:

• the CHANGELOG.md release notes have been updated to reflect significant changes

[pmalek]

For reference: change in 1.32 made CEL reserved keywords (like namespace) to be used kubernetes/kubernetes#126977.

This is the reason installing CRDs in Kubernetes versions older than 1.32 currently fails.

[mlavacca]

Cool, 🚢