provisioner-azure: Make it mandatory to provide client_id

Regardless of what authentication provisioner uses (be it service
principal based or az cli based), the CAA still needs client id, so make
it mandatory to provide client id.

Fixes confidential-containers#974

Signed-off-by: Suraj Deshmukh <suraj.deshmukh@microsoft.com>

test/provisioner/provision_azure_initializer.go

@@ -89,7 +89,11 @@ func initAzureProperties(properties map[string]string) error {
 	if AzureProps.SubscriptionID == "" {
 		return errors.New("AZURE_SUBSCRIPTION_ID was not set.")
 	}
-	if AzureProps.ClientID == "" && !AzureProps.IsAzCliAuth {
+
+	// TODO: Right now AZURE_CLIENT_ID can be used by the provisioner
+	// application and the same value is passed on to the CAA app inside the
+	// daemonset. Figure out a way to separate these two.
+	if AzureProps.ClientID == "" {
 		return errors.New("AZURE_CLIENT_ID was not set.")
 	}
 	if AzureProps.ClientSecret == "" && !AzureProps.IsAzCliAuth {