### 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_
snapshot.add_transformer(snapshot.transform.s3_api())
        # Ob
        # ht
        # pu
        object_key = "key-with-metadata"
        metadata = {"TEST_META_1": "foo", "__meta_2": "bar"}
        s3_client.put_object(Bucket=s3_bucket, Key=object_key, Metadata=metadata, Body="foo")
        metadata_saved = s3_client.head_object(Bucket=s3_bucket, Key=object_key)["Metadata"]
        snapshot.match("head-object", metadata_saved)
        # no
        assert metadata_saved == {"test_meta_1": "foo", "__meta_2": "bar"}
    @pytest.mark.aws_validated
    @pytest.mark.skip_snapshot_verify(paths=["$..VersionId", "$..ContentLanguage"])
    def test_upload_file_multipart(self, s3_client, s3_bucket, tmpdir, snapshot):
        snapshot.add_transformer(snapshot.transform.s3_api())
        key = "my-key"
        # ht
        config = TransferConfig(multipart_threshold=5 * KB, multipart_chunksize=1 * KB)
        file = tmpdir / "test-file.bin"
        data = b"1" * (6 * KB)  # cr
        file.write(data=data, mode="w")
        s3_client.upload_file(
            Bucket=s3_bucket, Key=key, Filename=str(file.realpath()), Config=config
        )
        obj = s3_client.get_object(Bucket=s3_bucket, Key=key)
        assert obj["Body"].read() == data, f"body did not contain expected data {obj}"
        snapshot.match("get_object", obj)
    @pytest.mark.aws_validated
    @pytest.mark.parametrize("delimiter", ["/", "%2F"])
    def test_list_objects_with_prefix(self, s3_client, s3_create_bucket, delimiter):