Correctly handle worker deletion process for hibernated shoots

```improvement user
All worker controllers are now making sure that the machine-controller-manager is awake before deleting the machines (in case the shoot was hibernated before). Also, they now ensure that the required RBAC roles have been created before starting the deletion process.
```

pkg/controller/worker/genericactuator/actuator_delete.go

@@ -26,8 +26,10 @@ import (
 
 	gardencorev1alpha1helper "github.com/gardener/gardener/pkg/apis/core/v1alpha1/helper"
 	extensionsv1alpha1 "github.com/gardener/gardener/pkg/apis/extensions/v1alpha1"
+	kutil "github.com/gardener/gardener/pkg/utils/kubernetes"
 	machinev1alpha1 "github.com/gardener/machine-controller-manager/pkg/apis/machine/v1alpha1"
 	"github.com/pkg/errors"
+	appsv1 "k8s.io/api/apps/v1"
 	"k8s.io/apimachinery/pkg/api/meta"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/util/wait"
@@ -45,6 +47,21 @@ func (a *genericActuator) Delete(ctx context.Context, worker *extensionsv1alpha1
 		return errors.Wrapf(err, "could not instantiate actuator context")
 	}
 
+	// Make sure machine-controller-manager is awake before deleting the machines.
+	deployment := &appsv1.Deployment{}
+	if err := a.client.Get(ctx, kutil.Key(worker.Namespace, a.mcmName), deployment); err != nil {
+		return err
+	}
+	if err := util.ScaleDeployment(ctx, a.client, deployment, 1); err != nil {
+		return err
+	}
+
+	// Make sure that all RBAC roles required by the machine-controller-manager exist in the shoot cluster.
+	// This code can be removed as soon as the RBAC roles are managed by the gardener-resource-manager.
+	if err := a.applyMachineControllerManagerShootChart(ctx, workerDelegate, worker, cluster); err != nil {
+		return errors.Wrapf(err, "could not apply machine-controller-manager shoot chart")
+	}
+
 	// Mark all existing machines to become forcefully deleted.
 	a.logger.Info("Deleting all machines", "worker", fmt.Sprintf("%s/%s", worker.Namespace, worker.Name))
 	if err := a.markAllMachinesForcefulDeletion(ctx, worker.Namespace); err != nil {

pkg/controller/worker/genericactuator/machine_controller_manager.go

@@ -63,19 +63,27 @@ func (a *genericActuator) deployMachineControllerManager(ctx context.Context, wo
 	}
 
 	if !controller.IsHibernated(cluster.Shoot) {
-		shootClients, err := util.NewClientsForShoot(ctx, a.client, workerObj.Namespace, client.Options{})
-		if err != nil {
+		if err := a.applyMachineControllerManagerShootChart(ctx, workerDelegate, workerObj, cluster); err != nil {
 			return err
 		}
+	}
 
-		mcmShootValues, err := workerDelegate.GetMachineControllerManagerShootChartValues(ctx)
-		if err != nil {
-			return err
-		}
+	return nil
+}
 
-		if err := a.mcmShootChart.Apply(ctx, shootClients.GardenerClientset(), shootClients.ChartApplier(), metav1.NamespaceSystem, cluster.Shoot, a.imageVector, nil, mcmShootValues); err != nil {
-			return errors.Wrapf(err, "could not apply MCM chart in seed for worker '%s'", util.ObjectName(workerObj))
-		}
+func (a *genericActuator) applyMachineControllerManagerShootChart(ctx context.Context, workerDelegate WorkerDelegate, workerObj *extensionsv1alpha1.Worker, cluster *controller.Cluster) error {
+	shootClients, err := util.NewClientsForShoot(ctx, a.client, workerObj.Namespace, client.Options{})
+	if err != nil {
+		return err
+	}
+
+	mcmShootValues, err := workerDelegate.GetMachineControllerManagerShootChartValues(ctx)
+	if err != nil {
+		return err
+	}
+
+	if err := a.mcmShootChart.Apply(ctx, shootClients.GardenerClientset(), shootClients.ChartApplier(), metav1.NamespaceSystem, cluster.Shoot, a.imageVector, nil, mcmShootValues); err != nil {
+		return errors.Wrapf(err, "could not apply MCM chart in seed for worker '%s'", util.ObjectName(workerObj))
 	}
 
 	return nil