### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

When you publish a message to SNS without a *body* (e.g. only attributes) it succeeds.

### Expected Behavior

Trying to publish a message without a *body* should fail (at least it does when trying to do this in AWS)

### How are you starting LocalStack?

Custom (please describe below)

### Steps To Reproduce

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

using Java testcontainers...

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

```bash
#!/bin/sh
 
queue_arn=$(awslocal sqs create-queue --queue-name $QUEUE_NAME --output text)
echo "Queue ARN: $queue_arn"

topic_arn=$(awslocal sns create-topic --name $TOPIC_NAME --output text)
echo "Topic ARN: $topic_arn"

subscription_arn=$(awslocal sns subscribe \
    --attributes RawMessageDelivery=true \
    --topic-arn "$topic_arn" \
    --protocol sqs \
    --notification-endpoint "$queue_arn" \
    --output text)
echo "Subscription ARN: $subscription_arn" 
```


### Environment

```markdown
- OS: OSX 11.5.2
- LocalStack: 0.13.0
- Docker Desktop: v20.10.8
```


### Anything else?

_No response_
subscription_arn = subscription["SubscriptionArn"]
            subscription_obj = sns_backend.subscription_status[subscription_arn]
            self.assertEqual(subscription_obj["Status"], "Not Subscribed")
            _token = subscription_obj["Token"]
            self.sns_client.confirm_subscription(TopicArn=self.topic_arn, Token=_token)
            self.assertEqual(subscription_obj["Status"], "Subscribed")
        retry(check_subscription, retries=PUBLICATION_RETRIES, sleep=PUBLICATION_TIMEOUT)
    def test_dead_letter_queue(self):
        lambda_name = "test-%s" % short_uid()
        lambda_arn = aws_stack.lambda_function_arn(lambda_name)
        topic_name = "test-%s" % short_uid()
        topic_arn = self.sns_client.create_topic(Name=topic_name)["TopicArn"]
        queue_name = "test-%s" % short_uid()
        queue_url = self.sqs_client.create_queue(QueueName=queue_name)["QueueUrl"]
        queue_arn = aws_stack.sqs_queue_arn(queue_name)
        testutil.create_lambda_function(
            func_name=lambda_name,
            handler_file=TEST_LAMBDA_PYTHON,
            libs=TEST_LAMBDA_LIBS,
            runtime=LAMBDA_RUNTIME_PYTHON36,
            DeadLetterConfig={"TargetArn": queue_arn},
        )
        self.sns_client.subscribe(TopicArn=topic_arn, Protocol="lambda", Endpoint=lambda_arn)
        payload = {
            lambda_integration.MSG_BODY_RAISE_ERROR_FLAG: 1,
        }
        self.sns_client.publish(TopicArn=topic_arn, Message=json.dumps(payload))
        def receive_dlq():