Upgrade Bucket overlay content to BucketV2

[t0yv0]

There is some content that uses TypeScript-only overlays like onObjectCreated with aws.s3.Bucket that is difficult to update to aws.s3.BucketV2 because the new resource does not yet support them (https://github.com/pulumi/pulumi-aws/issues/4475).

• content/docs/iac/clouds/aws/guides/lambda.md
• content/docs/iac/concepts/function-serialization.md
• content/topics/serverless.md
• static/programs/aws-lambda-container-thumbnailer-javascript/index.js