### 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.
return connect_to(aws_access_key_id=self.account_id, region_name=self.region_name).events
    def to_start_output(self) -> StartExecutionOutput:
        return StartExecutionOutput(executionArn=self.exec_arn, startDate=self.start_date)
    def to_describe_output(self) -> DescribeExecutionOutput:
        describe_output = DescribeExecutionOutput(
            executionArn=self.exec_arn,
            stateMachineArn=self.state_machine.arn,
            name=self.name,
            status=self.exec_status,
            startDate=self.start_date,
            stopDate=self.stop_date,
            input=to_json_str(self.input_data, separators=(",", ":")),
            inputDetails=self.input_details,
            traceHeader=self.trace_header,
        )
        if describe_output["status"] == ExecutionStatus.SUCCEEDED:
            describe_output["output"] = self.output
            describe_output["outputDetails"] = self.output_details
        if self.error is not None:
            describe_output["error"] = self.error
        if self.cause is not None:
            describe_output["cause"] = self.cause
        return describe_output
    def to_describe_state_machine_for_execution_output(