### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

Initiating a multipart S3 upload to LocalStack returns an XML document with a root element CreateMultipartUploadOutput. This causes an error in the ex_aws_s3 library I'm using. We've used the combination of LocalStack + ex_aws_s3 successfully for a few years and the error started occurring a few days ago.

### Expected Behavior

The element should be called InitiateMultipartUploadResult.

### How are you starting LocalStack?

With a `docker run` command

### Steps To Reproduce

#### How are you starting localstack (e.g., `bin/localstack` command, arguments, or `docker-compose.yml`)

    docker run -p 4566:4566 localstack/localstack

#### Client commands (e.g., AWS SDK code snippet, or sequence of "awslocal" commands)

    aws --debug --endpoint-url=http://localhost:4566 s3api create-multipart-upload --bucket my-bucket --key 'multipart/01'


### Environment

```markdown
- OS: Ubuntu 20.04.5 LTS
- LocalStack: latest
```


### Anything else?

S3 docs specifying InitiateMultipartUploadResult:
https://docs.aws.amazon.com/AmazonS3/latest/API/API_CreateMultipartUpload.html

Reference in official AWS Java client:
https://github.com/aws/aws-sdk-java/blob/ef22b94750d4c155d74b09012b3be5d9d98bbd33/aws-java-sdk-s3/src/main/java/com/amazonaws/services/s3/model/transform/XmlResponsesSaxParser.java#L1865

Where our particular error gets raised in ex_aws_s3:
https://github.com/ex-aws/ex_aws_s3/blob/7e12f2b0578b2620c047d2e44c40a6de8773584a/lib/ex_aws/s3/parsers.ex#L78
def __init__(self, message=None):
        super().__init__("MalformedACLError", status_code=400, message=message)
class InvalidRequest(CommonServiceException):
    def __init__(self, message=None):
        super().__init__("InvalidRequest", status_code=400, message=message)
class UnexpectedContent(CommonServiceException):
    def __init__(self, message=None):
        super().__init__("UnexpectedContent", status_code=400, message=message)
def get_full_default_bucket_location(bucket_name):
    if config.HOSTNAME_EXTERNAL != config.LOCALHOST:
        host_definition = localstack_host(
            use_hostname_external=True, custom_port=config.get_edge_port_http()
        )
        return f"{config.get_protocol()}://{host_definition.host_and_port()}/{bucket_name}/"
    else:
        host_definition = localstack_host(use_localhost_cloud=True)
        return f"{config.get_protocol()}://{bucket_name}.s3.{host_definition.host_and_port()}/"
class S3Provider(S3Api, ServiceLifecycleHook):
    @staticmethod
    def get_store() -> S3Store:
        return s3_stores[get_aws_account_id()][aws_stack.get_region()]
    def _clear_bucket_from_store(self, bucket: BucketName):
        store = self.get_store()
        store.bucket_lifecycle_configuration.pop(bucket, None)
        store.bucket_versioning_status.pop(bucket, None)
        store.bucket_cors.pop(bucket, None)
        store.bucket_notification_configs.pop(bucket, None)
        store.bucket_replication.pop(bucket, None)
        store.bucket_website_configuration.pop(bucket, None)
    def on_after_init(self):