### 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.
_tags: Final[dict[str, Optional[str]]]
    def __init__(self):
        self._tags = OrderedDict()
    @staticmethod
    def _validate_key_value(key: str) -> None:
        if not key:
            raise ValidationException()
    @staticmethod
    def _validate_tag_value(value: str) -> None:
        if value is None:
            raise ValidationException()
    def add_all(self, tags: TagList) -> None:
        for tag in tags:
            tag_key = tag["key"]
            tag_value = tag["value"]
            self._validate_key_value(key=tag_key)
            self._validate_tag_value(value=tag_value)
            self._tags[tag_key] = tag_value
    def remove_all(self, keys: TagKeyList):
        for key in keys:
            self._validate_key_value(key=key)
            self._tags.pop(key, None)
    def to_tag_list(self) -> TagList:
        tag_list = list()
        for key, value in self._tags.items():
            tag_list.append(Tag(key=key, value=value))
        return tag_list
class StateMachineRevision(StateMachineInstance):