This is a backport issue for #11360, automatically created via GitHub Actions workflow initiated by @gaktive

Original issue body:

Azure in-tree cloud provider has been removed for k8s >=1.30. We are adding docs on how to use External cloud provider for creating new Azure clusters and how to migrate from Azure to External cloud provider for k8s < 1.30.

This currently works with Edit as Yaml, but need the following changes in UI:

1. Remove Azure from cloud provider dropdown for RKE1 and RKE2 clusters >= k8s 1.30.
2. Allow changing cloud provider from Azure to External in dropdown for RKE1 and RKE2 clusters for k8s >= 1.27 && k8s < 1.30 so users can migrate before upgrading to v1.30.