### 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.
_PROGRAM_START_EVENT_ID: Final[int] = 0
    source_event_id: int
    last_published_event_id: int
    def __init__(self, previous_event_id: int):
        self.source_event_id = previous_event_id
        self.last_published_event_id = previous_event_id
    @classmethod
    def of_program_start(cls) -> EventHistoryContext:
        return cls(previous_event_id=cls._PROGRAM_START_EVENT_ID)
    def integrate(self, other: EventHistoryContext) -> None:
        self.source_event_id = max(self.source_event_id, other.source_event_id)
        self.last_published_event_id = max(
            self.last_published_event_id, other.last_published_event_id
        )
class EventIdGenerator:
    _next_id: int
    def __init__(self):
        self._next_id = 1
    def get(self) -> int:
        next_id = self._next_id
        self._next_id += 1
        return next_id
class EventHistory:
    _mutex: Final[threading.Lock]
    _history_event_list: Final[HistoryEventList]
    _event_id_gen: EventIdGenerator
    def __init__(self):