Prune LBC deployment

The Deployment's label selector is changing so we must prune it to prevent upgrade failures like in the manyaddons e2e tests

Author: rifelpet

upup/pkg/fi/cloudup/bootstrapchannelbuilder/bootstrapchannelbuilder.go

@@ -653,13 +653,14 @@ func (b *BootstrapChannelBuilder) buildAddons(c *fi.CloudupModelBuilderContext)
 			}
 			location := key + "/" + id + ".yaml"
 
-			addons.Add(&channelsapi.AddonSpec{
+			addon := addons.Add(&channelsapi.AddonSpec{
 				Name:     fi.PtrTo(key),
 				Selector: map[string]string{"k8s-addon": key},
 				Manifest: fi.PtrTo(location),
 				Id:       id,
 				NeedsPKI: true,
 			})
+			addon.BuildPrune = true
 
 			// Generate aws-load-balancer-controller ServiceAccount IAM permissions
 			if b.UseServiceAccountExternalPermissions() {