Align kubebuilder markers with shipped CRDs

[KhizerRehan]

What happened

The +kubebuilder:* markers on Machine, MachineSet and MachineDeployment no longer match the CRDs shipped in examples/machine-controller.yaml, so a controller-gen run would not be output-neutral.

Found while sweeping every CRD in a live cluster with kubectl explain <crd>.spec. All three cluster.k8s.io types failed:

error: field "spec" does not exist

That failure has its own cause — the shipped CRDs publish a stub schema (type: object plus x-kubernetes-preserve-unknown-fields: true, no properties), so explain has nothing to resolve past the root:

CRD	Schema in examples/machine-controller.yaml	explain .spec
machines.cluster.k8s.io	line 23, stub	field "spec" does not exist
machinesets.cluster.k8s.io	line 72, stub	field "spec" does not exist
machinedeployments.cluster.k8s.io	line 126, stub	field "spec" does not exist

Publishing a real structural schema is out of scope here and needs its own issue. Auditing the markers to explain the failure is what turned up three mismatches against the shipped CRDs:

Fix: markers follow the shipped YAML. No change to CRD YAML, controller behaviour, or kubectl get output.