### 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
```
queue_url = sqs_create_queue()
        msg_attrs_provider = {"timestamp": {"StringValue": "1493147359900", "DataType": "Number"}}
        aws_trace_header = {
            "AWSTraceHeader": {
                "StringValue": "Root=1-5759e988-bd862e3fe1be46a994272793;Parent=53995c3f42cd8ad8;Sampled=1",
                "DataType": "String",
            }
        }
        response_send = sqs_client.send_message(
            QueueUrl=queue_url, MessageBody="test", MessageAttributes=msg_attrs_provider
        )
        response_send_system_attr = sqs_client.send_message(
            QueueUrl=queue_url,
            MessageBody="test",
            MessageAttributes=msg_attrs_provider,
            MessageSystemAttributes=aws_trace_header,
        )
        assert (
            response_send["MD5OfMessageAttributes"]
            == response_send_system_attr["MD5OfMessageAttributes"]
        )
        assert response_send.get("MD5OfMessageSystemAttributes") is None
        assert (
            response_send_system_attr.get("MD5OfMessageSystemAttributes")
            == "5ae4d5d7636402d80f4eb6d213245a88"
        )
    def test_inflight_message_requeue(self, sqs_client, sqs_create_queue):