chore: remove unnecessary comment (#1309)

Remove unnecessary comment from test fixture.

---
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Author: 9pace

packages/@aws-cdk-testing/cli-integ/resources/cdk-apps/nested-stack-with-fn-join-export/app.js

@@ -2,8 +2,6 @@ const cdk = require('aws-cdk-lib');
 const { aws_cloudformation: cfn, aws_sns: sns, aws_ssm: ssm } = cdk;
 
 /**
- * Reproduces https://t.corp.amazon.com/D423570178
- *
  * When IncludeNestedStacks is true, CloudFormation validates all nested stacks
  * together. Export names using Fn::Join with a runtime reference get collapsed
  * to the placeholder {{IntrinsicFunction://Fn::Join}}, causing a false