📊Tracking: upgrade to Node 20

### Overview (updated 1/30/25)

Node 18, which is currently in its Active LTS phase, is slated to reach its End of Life on 2025-04-30, as indicated on https://nodejs.dev/en/about/releases/.
Our aim is to provide CDK users with sufficient preparation time to update their CDK code to the latest LTS Node version (Node 20) before it becomes unsupported for deployed resources such as Lambda and Custom Resources.

Node 20 and 22 are available in CDK but are not the default for Lambda as not every region yet supports them, however it is available in Commercial, China and Gov Cloud regions. We recommend you use an explicit Node version such as NODEJS_22_X (rather than NODEJS_LATEST). The default NODEJS_LATEST will be updated once all regions support Node 20 (or 22).

For custom constructs the regional defaults for custom constructs in Commercial are now Node 20. The regional defaults for custom constructs in China and Gov Cloud regions have been updated to Node 20 and will be in the next release (expected 2/5/25)

### Link to the service’s CDK Construct Library API reference page.

N/A

### Maturity: CloudFormation Resources Only

Stable

### Implementation

TBD

### Issue list

- aws/aws-cdk/issues/28125
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