### 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_
def forward_request(self, method, path, data, headers):
                records.append((json.loads(to_str(data)), headers))
                return 429
        number_of_subscriptions = 4
        records = []
        proxies = []
        for _ in range(number_of_subscriptions):
            local_port = get_free_tcp_port()
            proxies.append(
                start_proxy(local_port, backend_url=None, update_listener=MyUpdateListener())
            )
            wait_for_port_open(local_port)
            http_endpoint = "%s://localhost:%s" % (get_service_protocol(), local_port)
            self.sns_client.subscribe(
                TopicArn=self.topic_arn, Protocol="http", Endpoint=http_endpoint
            )
        # f
        subscription_list = self.sns_client.list_subscriptions()
        self.assertEqual(subscription_list["ResponseMetadata"]["HTTPStatusCode"], 200)
        self.assertEqual(len(subscription_list["Subscriptions"]), number_of_subscriptions)
        self.assertEqual(number_of_subscriptions, len(records))
        for proxy in proxies:
            proxy.stop()
    def _create_queue(self):