Fix default k8s snap channel

This commit ensures that the "-classic/edge" channel is used if
no snap channel, revision or path is provided.

We cannot use "stable" since we don't have a stable channel yet.

pkg/cloudinit/common.go

@@ -73,10 +73,11 @@ func NewBaseCloudConfig(data BaseUserData) (CloudConfig, error) {
 
 	snapInstall := data.SnapInstallData
 	// Default to k8s version if snap install option is not set or empty.
-	if snapInstall == nil {
+	if snapInstall == nil || snapInstall.Option == "" {
+		// TODO: consider using "stable" once we'll have a stable channel.
 		snapInstall = &SnapInstallData{
 			Option: InstallOptionChannel,
-			Value:  fmt.Sprintf("%d.%d-classic/stable", kubernetesVersion.Major(), kubernetesVersion.Minor()),
+			Value:  fmt.Sprintf("%d.%d-classic/edge", kubernetesVersion.Major(), kubernetesVersion.Minor()),
 		}
 	}