The controller doesn't generate `%s-generated-kubeletconfig-%s` files for new MCPs

We have an OKD cluster with approximately 10 MachineConfigPools (MCPs) that inherit from the worker MCP. When we add a new MCP, the 97 and 98 kubelet configurations are not generated for it. They are only created after restarting the Machine Config Controller pod. I suspect this happens because the kubelet config controller does not register any event handlers on the [MCP informer](https://github.com/openshift/machine-config-operator/blob/main/pkg/controller/kubelet-config/kubelet_config_controller.go#L109). As a result, adding a new MCP does not trigger reconciliation. When the operator is restarted, the FeatureGate informer emits an initial `ADD` event, which then triggers reconciliation and leads to the generation of the missing kubeletConfigs. To reproduce the issue, watch the MachineConfigs (`oc get machineconfig -w`) and apply a new MCP, for example, as shown below. The expected behavior is that three MachineConfigs are generated: `97-demo-generated-kubelet`, `98-demo-generated-kubelet`, and `rendered-demo-uuid`. In practice, only `rendered-demo-uuid` is created. The 97 and 98 kubelet MachineConfigs are generated only after the controller pod is restarted. ```yaml apiVersion: machineconfiguration.openshift.io/v1 kind: MachineConfigPool metadata: labels: machineconfiguration.openshift.io/role: demo pools.operator.machineconfiguration.openshift.io/demo: "" name: demo spec: machineConfigSelector: matchExpressions: - key: machineconfiguration.openshift.io/role operator: In values: - worker - demo maxUnavailable: 1 nodeSelector: matchLabels: node-role.kubernetes.io/demo: "" paused: false ```