### 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_
remove=container_config.remove,
            network=container_config.network,
            env_vars=container_config.env_vars,
            dns=container_config.dns,
            additional_flags=container_config.additional_flags,
            ports=container_config.ports,
            command=container_config.command,
            mount_volumes=container_config.volumes,
            workdir=container_config.workdir,
            user=container_config.user,
            cap_add=container_config.cap_add,
        )
        if config.LAMBDA_REMOTE_DOCKER:
            for source, target in container_config.required_files:
                DOCKER_CLIENT.copy_into_container(container_id, source, target)
        return DOCKER_CLIENT.start_container(
            container_id,
            interactive=not container_config.detach,
            attach=not container_config.detach,
            stdin=stdin,
        )
class LambdaExecutorLocal(LambdaExecutor):
    
    FUNCTION_CALLABLES: Dict[str, Dict[str, Callable]] = {}
    def _execute_in_custom_runtime(
        self, cmd: Union[str, List[str]], lambda_function: LambdaFunction = None
    ) -> InvocationResult:
        """
        Generic run function for executing lambdas in custom runtimes.
        :param cmd: the command to execute