### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

I'm executing a state machine using the following definition:

```json
{
  "StartAt": "Parallel",
  "States": {
    "Parallel": {
      "Type": "Parallel",
      "Branches": [
        {
          "StartAt": "BranchA",
          "States": {
            "BranchA": {
              "Type": "Pass",
              "Result": {
                "branch": "A"
              },
              "End": true
            }
          }
        },
        {
          "StartAt": "BranchB",
          "States": {
            "BranchB": {
              "Type": "Pass",
              "Result": {
                "branch": "B"
              },
              "End": true
            }
          }
        }
      ],
      "End": true
    }
  }
}
```

I get the following output:

```json
[
  {
    "branch": "B"
  },
  {
    "branch": "A"
  }
]
```

The results are not in the correct order. The result from branch A should always be first even when the branch A is slower, and the result from branch B should always be second.

### Expected Behavior

The output should be:

```json
[
  {
    "branch": "A"
  },
  {
    "branch": "B"
  }
]
```

### How are you starting LocalStack?

With a docker-compose file

### Steps To Reproduce

Create and execute a state machine using the provided definition.

### Environment

```markdown
- LocalStack: 3.0.3.dev20231207105008
```


### Anything else?

_No response_
):
        bucket_name = s3_create_bucket()
        sfn_snapshot.add_transformer(RegexTransformer(bucket_name, "bucket-name"))
        key = "file.csv"
        csv_file = (
            "0,True,{}\n"
            "Value4,Value5,Value6\n"
            ",,,\n"
            "true,1,'HelloWorld'\n"
            "Null,None,\n"
            "   \n"
        )
        aws_client.s3.put_object(Bucket=bucket_name, Key=key, Body=csv_file)
        template = ST.load_sfn_template(ST.MAP_ITEM_READER_BASE_CSV_HEADERS_FIRST_LINE)
        definition = json.dumps(template)
        exec_input = json.dumps({"Bucket": bucket_name, "Key": key})
        create_and_record_execution(
            aws_client.stepfunctions,
            create_iam_role_for_sfn,
            create_state_machine,
            sfn_snapshot,
            definition,
            exec_input,
        )
    @markers.aws.validated
    def test_map_item_reader_csv_headers_decl_extra_fields(
        self,
        aws_client,
        s3_create_bucket,
        create_iam_role_for_sfn,