MULTIARCH-4569: aws: support multi-arch nodes

Use different instance types based on the node's architecture.

Author: r4f4

pkg/asset/machines/worker.go

@@ -399,7 +399,11 @@ func (w *Worker) Generate(ctx context.Context, dependencies asset.Parents) error
 			}
 
 			if mpool.InstanceType == "" {
-				instanceTypes := awsdefaults.InstanceTypes(installConfig.Config.Platform.AWS.Region, installConfig.Config.ControlPlane.Architecture, configv1.HighlyAvailableTopologyMode)
+				arch := installConfig.Config.ControlPlane.Architecture
+				if len(installConfig.Config.Compute) > 0 {
+					arch = installConfig.Config.Compute[0].Architecture
+				}
+				instanceTypes := awsdefaults.InstanceTypes(installConfig.Config.Platform.AWS.Region, arch, configv1.HighlyAvailableTopologyMode)
 				switch pool.Name {
 				case types.MachinePoolEdgeRoleName:
 					ok := awsSetPreferredInstanceByEdgeZone(ctx, instanceTypes, installConfig.AWS, zones)