### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

Currently, when passing `$$.Execution.StartTime` as a parameter to a SFN lambda, it is coming in in the format `HH:MM:SS.###`.

### Expected Behavior

`$$.Execution.StartTime` should be an ISO 8601 datetime string.

### How are you starting LocalStack?

With a docker-compose file

### Steps To Reproduce

This is run in a docker compose file.

Step function definition is

```json
{
  "Comment": "Sample SFN",
  "StartAt": "SampleLambda",
  "States": {    
    "SampleLambda": {
      "Type": "Task",
      "Resource": "arn:aws:states:::lambda:invoke",
      "End": true,
      "Parameters": {
        "FunctionName": "Sample-Function",
        "Payload": {
          "data": {
            "startDateTime.$": "$$.Execution.StartTime"
          }
        }
      }
    }
  }
}
```

### Environment

```markdown
- OS: Mac OS Ventura 13.6.1
- LocalStack:
LocalStack version: 3.0.1.dev
LocalStack build date: 2023-11-20
LocalStack build git hash: 3e32b438
```


### Anything else?

Thank you so much for your hard work.
self,
        context: RequestContext,
        task_token: TaskToken,
        error: SensitiveError = None,
        cause: SensitiveCause = None,
    ) -> SendTaskFailureOutput:
        outcome = CallbackOutcomeFailure(callback_id=task_token, error=error, cause=cause)
        store = self.get_store(context)
        for execution in store.executions.values():
            try:
                if execution.exec_worker.env.callback_pool_manager.notify(
                    callback_id=task_token, outcome=outcome
                ):
                    return SendTaskFailureOutput()
            except CallbackNotifyConsumerError as consumer_error:
                if isinstance(consumer_error, CallbackConsumerTimeout):
                    raise TaskTimedOut()
                else:
                    raise TaskDoesNotExist()
        raise InvalidToken()
    def start_execution(