### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

If the Lambda returns an error, the message is put into DLQ straightaway after first try **although** the configurations says "try 3 times".

### Expected Behavior

If the Lambda returns an error, the message should be put into DLQ after what `RedrivePolicy.maxReceiveCount` says which is 3 in this case. For instance, try processing the message 3 times, if still no success, put it into DLQ.

### How are you starting LocalStack?

With a docker-compose file

### Steps To Reproduce

```yaml
version: "3.8"

services:
  localstack:
    image: "localstack/localstack"
    container_name: "localstack"
    ports:
      - "4566-4599:4566-4599"
    environment:
      - DEBUG=1
      - DEFAULT_REGION=eu-west-1
      - SERVICES=lambda,events,sqs
      - DATA_DIR=/tmp/localstack/data
      - DOCKER_HOST=unix:///var/run/docker.sock
      - LAMBDA_EXECUTOR=docker
    volumes:
      - "./tmp/localstack:/tmp/localstack"
      - "/var/run/docker.sock:/var/run/docker.sock"
```

### Environment

```markdown
- OS: MacOS BigSur
- LocalStack: `1dc090777b0c`
```


### Anything else?

This will try **only once** and put the message into DLQ after failure **although** the retry policy instructs for **3 retries**. This is the issue.

```bash
aws --profile localstack --endpoint-url http://localhost:4566 lambda create-function \
    --function-name api-lambda \
    --handler lambda/main \
    --runtime go1.x \
    --role api-role \
    --zip-file fileb://lambda.zip
    
aws --profile localstack --endpoint-url http://localhost:4566 sqs create-queue \
    --queue-name api-dead-letter-queue

aws --profile localstack --endpoint-url http://localhost:4566 sqs create-queue \
    --queue-name api-queue \
    --attributes '{"RedrivePolicy":"{\"deadLetterTargetArn\":\"arn:aws:sqs:eu-west-1:000000000000:api-dead-letter-queue\",\"maxReceiveCount\":\"3\"}"}'

aws --profile localstack --endpoint-url http://localhost:4566 lambda create-event-source-mapping \
    --function-name api-lambda \
    --event-source-arn arn:aws:sqs:eu-west-1:000000000000:api-queue
```

Use this command to test.

```bash
aws --profile localstack --endpoint-url http://localhost:4566 sqs send-message \
    --queue-url http://localhost:4566/000000000000/api-queue \
    --message-body '{"hello":"world"}'
```

----

FYI - This will try **indefinitely** (_30 sec in between_) until it succeeds because there is **no** retry policy set which is perfectly normal and expected behaviour.

```bash
aws --profile localstack --endpoint-url http://localhost:4566 lambda create-function \
    --function-name api-lambda \
    --handler lambda/main \
    --runtime go1.x \
    --role api-role \
    --zip-file fileb://lambda.zip
    
aws --profile localstack --endpoint-url http://localhost:4566 sqs create-queue \
    --queue-name api-dead-letter-queue

aws --profile localstack --endpoint-url http://localhost:4566 sqs create-queue \
    --queue-name api-queue

aws --profile localstack --endpoint-url http://localhost:4566 lambda create-event-source-mapping \
    --function-name api-lambda \
    --event-source-arn arn:aws:sqs:eu-west-1:000000000000:api-queue
```
"MessageBody": event,
                "MessageAttributes": custom_attrs,
            }
        )
    elif ":lambda:" in source_arn:
        if event.get("Records") and "sns" in event["Records"][0]["EventSource"]:
            for record in event["Records"]:
                sns_rec = record.get("Sns", {})
                message_attrs = {**sns_rec.get("MessageAttributes"), **custom_attrs}
                messages.append(
                    {
                        "Id": sns_rec.get("MessageId"),
                        "MessageBody": sns_rec.get("Message"),
                        "MessageAttributes": message_attrs,
                    }
                )
        else:
            messages.append(
                {
                    "Id": str(uuid.uuid4()),
                    "MessageBody": json.dumps(event),
                    "MessageAttributes": custom_attrs,
                }
            )
    
    for message in messages:
        if message.get("MessageAttributes"):
            message["MessageAttributes"] = convert_to_printable_chars(message["MessageAttributes"])
    return messages
def message_attributes_to_upper(message_attrs: Dict) -> Dict: