[Feature] More (optional) control over watchdog traffic alarm: Add `datapointsToAlarm`

**Is your feature request related to a problem? Please describe.**
[datapointsToAlarm](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_cloudwatch.Alarm.html#datapointstoalarm) lets you skip datapoints, if the container gets hit once and drops back down. Could be useful for some containers, but default without it.

Start by locating the watchdog traffic alarm construction in the AWS CDK code and inspect how its alarm options are configured. Add optional support for datapointsToAlarm while preserving the default behavior when it is not provided, then verify the generated alarm configuration if tests or synthesis checks are available.

Written by the indexing model from the issue text.