### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

There is an issue with `get-object-attributes` command which results in below error always: 
`aws --endpoint-url=http://localhost:4566 s3api get-object-attributes --bucket s3mock --key 20.txt --object-attributes "ObjectSize"`
````

> Response:  Unable to parse response (syntax error: line 1, column 0), invalid XML received. Further retries may succeed:
b'98\n5\n'
````

### How are you starting LocalStack?

With a docker-compose file

### Steps To Reproduce

#### Using docker-compse.yaml to start localstack

docker-compse.yaml:

```
localstack:
    image: localstack/localstack:latest
    ports:
      - '4563-4599:4563-4599'
      - '8055:8080'
    environment:
      - SERVICES=s3
      - DEBUG=1
      - LS_LOG=error
      - DATA_DIR=/tmp/localstack/data
      - AWS_DEFAULT_REGION=eu-west-1
      # - EDGE_PORT=4566
    volumes:
      - "./.localstack:/tmp/localstack"
      - "/var/run/docker.sock:/var/run/docker.sock"
```

#### cli commands to reproduce the issue

1. Create a Bucket: `aws --endpoint-url=http://localhost:4566 s3 mb s3://s3mock`
2. Create an Object: `aws --endpoint-url=http://localhost:4566 s3 cp data/20.txt s3://s3mock`

File 20.txt content are 2-digit numbers separated by newline.

3. get-object-attributes for object 20.txt :
```

 aws --endpoint-url=http://localhost:4566 s3api get-object-attributes --bucket s3mock --key 20.txt --object-attributes "ObjectSize"

```
Results in error:

> Unable to parse response (syntax error: line 1, column 0), invalid XML received. Further retries may succeed:
b'98\n5\n'



### Environment

```markdown
- OS:Mac 12.x
- LocalStack:latest
- Node 14
```


### Anything else?

_No response_
key_shape = shape.key
        value_shape = shape.value
        for key, value in value.items():
            actual_key = self._parse_shape(request, key_shape, key, uri_params)
            actual_value = self._parse_shape(request, value_shape, value, uri_params)
            parsed[actual_key] = actual_value
        n parsed
    def _parse_body_as_json(self, request: HttpRequest) -> dict:
        body_contents = request.data
        if not body_contents:
            n {}
        if request.mimetype.startswith("application/x-amz-cbor"):
            try:
                n cbor2.loads(body_contents)
            except ValueError as e:
                raise ProtocolParserError("HTTP body could not be parsed as CBOR.") from e
        else:
            try:
                n request.get_json(force=True)
            except BadRequest as e:
                raise ProtocolParserError("HTTP body could not be parsed as JSON.") from e
    def _parse_boolean(
        self, request: HttpRequest, shape: Shape, node: bool, uri_params: Mapping[str, Any] = None
    ) -> bool:
        n super()._noop_parser(request, shape, node, uri_params)
class JSONRequesr(BaseJSONRequesr):
    """
    The ``JSONRequesr`` is responsible for parsing incoming requests for services which use the ``json``
    protocol.
    The requests for these services encode the majority of their parameters as JSON in the request body.