chore(lambda): deprecate Node.js v16 runtime (aws#30842)

### Reason for this change
As documented, the Node.js v16 runtime was deprecated on June 12, 2024.
https://docs.aws.amazon.com/lambda/latest/dg/lambda-runtimes.html

### Description of changes



### Description of how you validated changes



### 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*

packages/aws-cdk-lib/aws-lambda/lib/runtime.ts

@@ -98,6 +98,7 @@ export class Runtime {
 
   /**
    * The NodeJS 16.x runtime (nodejs16.x)
+   * @deprecated Legacy runtime no longer supported by AWS Lambda. Migrate to the latest NodeJS runtime.
    */
   public static readonly NODEJS_16_X = new Runtime('nodejs16.x', RuntimeFamily.NODEJS, { supportsInlineCode: true });