fix(lambda): add dashboard widgets properly (#576)

Fixes regression from #574.

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Author: Eugene Cheung

lib/monitoring/aws-lambda/LambdaFunctionMonitoring.ts

@@ -612,6 +612,7 @@ export class LambdaFunctionMonitoring extends Monitoring {
         ),
       );
     }
+    widgets.push(secondRow);
 
     if (this.lambdaInsightsEnabled) {
       widgets.push(