### 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_
runtime = lambda_function.runtime
        env_vars = inv_context.environment
        
        with self.docker_container_lock:
            env_vars["_LAMBDA_SERVER_PORT"] = str(self.next_port + self.port_offset)
            self.next_port = (self.next_port + 1) % self.max_port
        
        LOG.debug(
            'Priming docker container with runtime "%s" and arn "%s".',
            runtime,
            func_arn,
        )
        container_info = self.prime_docker_container(
            lambda_function, dict(env_vars), lambda_cwd, inv_context.docker_flags
        )
        if not inv_context.lambda_command and inv_context.handler:
            command = shlex.split(container_info.entry_point)
            command.append(inv_context.handler)
            inv_context.lambda_command = command
        lambda_docker_ip = DOCKER_CLIENT.get_container_ip(container_info.name)
        if not self._should_use_stay_open_mode(lambda_function, lambda_docker_ip, check_port=True):
            LOG.debug("Using 'docker exec' to run invocation in docker-reuse Lambda container")
            
            env_vars["DOCKER_LAMBDA_STAY_OPEN"] = None
            return DOCKER_CLIENT.exec_in_container(
                container_name_or_id=container_info.name,
                command=inv_context.lambda_command,
                interactive=True,
                env_vars=env_vars,
                stdin=stdin,