Run conformance tests for Kubernetes 1.27

[stefanprodan]

Update the e2e test matrix to the latest supported Kubernetes versions.

[stefanprodan]

⚠️ We recommend Flux users to not upgrade to Kubernetes v1.27.0.

Tests are passing because Flux retires the apply, but Kubernetes 1.27.0 seems to have a bug where the server-side apply fails sometimes with a conversion error:

Kustomization/apps/podinfo dry-run failed,
error: failed to prune fields: failed add back owned items: failed to convert pruned object
at version kustomize.toolkit.fluxcd.io/v1: conversion for kustomize.toolkit.fluxcd.io/v1, Kind=Kustomization
returned invalid metadata in object at index 1: missing metadata in converted object

This is also the case with kubectl:

$ kubectl apply --server-side --dry-run=server -fclusters/my-clusters/image-repo.yaml --field-manager=kustomize-controller
imagerepository.image.toolkit.fluxcd.io/podinfo serverside-applied (server dry run)
imagerepository.image.toolkit.fluxcd.io/podinfo-acr serverside-applied (server dry run)
Error from server: failed to prune fields: failed add back owned items: failed to convert pruned object at version image.toolkit.fluxcd.io/v1beta2: conversion for image.toolkit.fluxcd.io/v1beta2, Kind=ImagePolicy returned invalid metadata in object at index 1: missing metadata in converted object
Error from server: failed to prune fields: failed add back owned items: failed to convert pruned object at version image.toolkit.fluxcd.io/v1beta2: conversion for image.toolkit.fluxcd.io/v1beta2, Kind=ImagePolicy returned invalid metadata in object at index 1: missing metadata in converted object

[stefanprodan]

Upstream issue kubernetes/kubernetes#117260

[stefanprodan]

The issue was fixed in Kubernetes 1.27.1, but currently there is no kind node image for it.