Fix cluster DNS IP format in Bottlerocket userdata (#1389)

* Fix cluster DNS format in Bottlerocket userdata

Bottlerocket, like AL2, also only supports a single cluster DNS IP. This
change matches Bottlerocket behavior to the existing AL2 one.

* Fix condition for Bottlerocket DNS settings

Co-authored-by: Brandon Wagner <bmwagner10@gmail.com>

* Fix file formatting

Co-authored-by: Brandon Wagner <bmwagner10@gmail.com>

pkg/cloudprovider/aws/launchtemplate.go

@@ -288,8 +288,8 @@ func (p *LaunchTemplateProvider) getUserData(ctx context.Context, constraints *v
 
 func (p *LaunchTemplateProvider) getBottlerocketUserData(ctx context.Context, constraints *v1alpha1.Constraints, additionalLabels map[string]string, caBundle *string) string {
 	userData := fmt.Sprintf("[settings.kubernetes]\ncluster-name = \"%s\"\napi-server = \"%s\"\n", injection.GetOptions(ctx).ClusterName, injection.GetOptions(ctx).ClusterEndpoint)
-	if constraints.KubeletConfiguration.ClusterDNS != nil {
-		userData += fmt.Sprintf("cluster-dns-ip = \"%s\"\n", constraints.KubeletConfiguration.ClusterDNS)
+	if len(constraints.KubeletConfiguration.ClusterDNS) > 0 {
+		userData += fmt.Sprintf("cluster-dns-ip = \"%s\"\n", constraints.KubeletConfiguration.ClusterDNS[0])
 	}
 	if caBundle != nil {
 		userData += fmt.Sprintf("cluster-certificate = \"%s\"\n", *caBundle)