Update RKE2 ClusterClass to v1beta2 and bump provider to v0.24.3

[mboersma]

What type of PR is this?

/kind failing-test

What this PR does / why we need it:

The RKE2 clusterclass e2e test is currently pinned to RKE2 provider v0.21.1 because newer versions changed the schema for RKE2ControlPlaneTemplate and RKE2ConfigTemplate. Specifically, rancher/cluster-api-provider-rke2#793 and #794 (released in v0.22.0) introduced a v1beta2 API and the v1beta2 contract: RKE2ControlPlane.spec.machineTemplate is no longer the InfrastructureRef container itself, but now wraps a Spec field that holds infrastructureRef (of type ContractVersionedObjectReference). CAPI v1.13's topology controller writes against this new contract and produced the schema error reported in #6081.

This PR updates our RKE2 clusterclass templates to use the v1beta2 API for RKE2 types and bumps the pinned provider version to v0.24.3 (latest stable):

• RKE2ControlPlaneTemplate and RKE2ConfigTemplate apiVersions changed from v1beta1 to v1beta2 in both base flavor (templates/flavors/clusterclass-rke2/) and the CI overlay (templates/test/ci/prow-clusterclass-ci-rke2/).
• ClusterClass controlPlane.ref and worker bootstrap.ref updated to v1beta2 for the RKE2 types. The ClusterClass itself stays on cluster.x-k8s.io/v1beta1, matching the rest of CAPZ.
• All ClusterClass patch selectors targeting RKE2 types updated to v1beta2.
• Webhook-readiness dry-run snippet in azure_test.go updated to v1beta2.
• RKE2 provider pin bumped from v0.21.1 to v0.24.3.
• Rendered cluster templates regenerated via make generate-flavors.

The patches that reference built-in topology variables ({{ .builtin.controlPlane.machineTemplate.infrastructureRef.name }}, {{ .builtin.machineDeployment.infrastructureRef.name }}) are unchanged — those built-in names persist across the contract version.

Which issue(s) this PR fixes:
Fixes #6081

Special notes for your reviewer:

The actual validation of this fix is pull-cluster-api-provider-azure-e2e-optional. Local checks (go vet -tags=e2e, make lint, make generate) all pass cleanly.

This effectively reverts the temporary pin in #6085 while raising the pin to a maintained release.

TODOs:

• squashed commits
• includes documentation
• adds unit tests
• cherry-pick candidate

Release note:

NONE

[mboersma]

/test pull-cluster-api-provider-azure-e2e-optional

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 43.88%. Comparing base (bd1e799) to head (29c5828).
⚠️ Report is 16 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6279   +/-   ##
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  Coverage   43.88%   43.88%           
=======================================
  Files         289      289           
  Lines       25351    25351           
=======================================
  Hits        11125    11125           
  Misses      13448    13448           
  Partials      778      778           

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[mboersma]

/retest

[willie-yao]

/lgtm
/approve

[k8s-ci-robot]

LGTM label has been added.

Details

Git tree hash: f3c55d404c8f159a0b5ef95bdc8b8b0e2ffdbbc1

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: willie-yao

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