clastix/cluster-api-control-plane-provider-kamaji

AI Summary: The Kamaji Cluster API Control Plane provider is encountering an error when updating TenantControlPlanes because it doesn't support unsetting the `dataStoreUsername` field. The task is to investigate why the provider is failing to handle the unset operation, and implement the necessary changes to support it. This likely involves modifying the provider's reconciliation logic to correctly handle cases where `dataStoreUsername` is absent or explicitly set to null. Testing will be required to ensure the fix works correctly and doesn't introduce regressions.