### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

It seems that it is possible to receive sns message in an sqs listener if there is a filterpolicy in place for null value in a message attribute, and a message is being sent without the message attribute.

### Expected Behavior

Don't recieve these type of messages

### How are you starting LocalStack?

With a docker-compose file

### Steps To Reproduce

`sns subscribe --topic-arn "demoTopicArn"  --protocol sqs --notification-endpoint "demoSqsEndpoint" --attributes '{"RawMessageDelivery": "true"}'`
`sns set-subscription-attributes --subscription-arn demoSubsArn --attribute-name FilterPolicy --attribute-value '{"testForNull": [null,{"anything-but": ["notgood"]}]}'`
`sns publish --topic-arn demoTopicArn --message "testforrecieval"`
`sqs receive-message --queue-url  "demoUrl"`

### Environment

```markdown
- OS: macOS 13.6
- LocalStack: 2.2.0
```


### Anything else?

_No response_
"""
    The HTTP(S) publisher is responsible for publishing the SNS message to an external HTTP(S) endpoint which subscribed
    to the topic. It will create an HTTP POST request to be sent to the endpoint.
    See https://docs.aws.amazon.com/sns/latest/dg/sns-http-https-endpoint-as-subscriber.html
    """
    def _publish(self, context: SnsPublishContext, subscriber: SnsSubscription):
        message_context = context.message
        message_body = self.prepare_message(message_context, subscriber)
        try:
            message_headers = {
                "Content-Type": "text/plain",
                
                
                "x-amz-sns-message-type": message_context.type,
                "x-amz-sns-message-id": message_context.message_id,
                "x-amz-sns-topic-arn": subscriber["TopicArn"],
                "User-Agent": "Amazon Simple Notification Service Agent",
            }
            if message_context.type != "SubscriptionConfirmation":
                
                message_headers["x-amz-sns-subscription-arn"] = subscriber["SubscriptionArn"]
            
            
            
            elif message_context.type == "Notification" and is_raw_message_delivery(subscriber):
                message_headers["x-amz-sns-rawdelivery"] = "true"