### Is there an existing issue for this?

- [X] I have searched the existing issues

### Feature description

The use case I have in mind is to run Node 16.x Lambdas - the default container registry is `lambci/lambda` which is effectively abandoned. [Not even Node 14.x has been published](https://github.com/lambci/docker-lambda/pull/330). However, switching the registry over to [`amazon/aws-lambda-nodejs`](https://hub.docker.com/r/amazon/aws-lambda-nodejs) still fails to pull the container, since localstack is looking for the tag `nodejs16.x`. I'd like to be able to specify that if the runtime is `nodejs16.x` it just looks for tag `16`.

### 🧑‍💻 Implementation

_No response_

### Anything else?

_No response_
self,
        lambda_function: LambdaFunction,
        lambda_docker_ip: Optional[str] = None,
        check_port: bool = False,
    ) -> bool:
        """Return whether to use stay-open execution mode - if we're running in Docker, the given IP
        is defined, and if the target API endpoint is available (optionally, if check_port is True)."""
        if not lambda_docker_ip:
            func_arn = lambda_function.arn()
            container_name = self.get_container_name(func_arn)
            lambda_docker_ip = DOCKER_CLIENT.get_container_ip(container_name_or_id=container_name)
        should_use = lambda_docker_ip and config.LAMBDA_STAY_OPEN_MODE
        if not should_use or not check_port:
            return should_use
        full_url = self._get_lambda_stay_open_url(lambda_docker_ip)
        return is_port_open(full_url)
    def _get_lambda_stay_open_url(self, lambda_docker_ip: str) -> str:
        return f"http://{lambda_docker_ip}:{STAY_OPEN_API_PORT}"
    def _execute(self, func_arn: str, *args, **kwargs) -> InvocationResult:
        if not LAMBDA_CONCURRENCY_LOCK.get(func_arn):
            concurrency_lock = threading.RLock()
            LAMBDA_CONCURRENCY_LOCK[func_arn] = concurrency_lock
        with LAMBDA_CONCURRENCY_LOCK[func_arn]:
            return super(LambdaExecutorReuseContainers, self)._execute(func_arn, *args, **kwargs)
    def startup(self):
        self.cleanup()
        
        if config.LAMBDA_REMOVE_CONTAINERS:
            self.start_idle_container_destroyer_interval()
    def cleanup(self, arn: str = None):