chore(synthetics): add nodejs puppeteer 8 runtime (#30851)

### Issue # (if applicable)

Closes #30850.

### Reason for this change

Add new runtime

https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/CloudWatch_Synthetics_Library_nodejs_puppeteer.html#CloudWatch_Synthetics_runtimeversion-nodejs-puppeteer-8.0

### Description of changes

Add new runtime



### Description of how you validated changes

No test added because just add runtime enum.



### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

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*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*