### 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._stdout = stdout
        self._stderr = stderr
    def stderr_formatted(self, truncated_to: int = LAMBDA_TRUNCATE_STDOUT):
        return truncate(to_str(self._stderr).strip().replace("\n", "\n> "), truncated_to)
    def stdout_formatted(self, truncated_to: int = LAMBDA_TRUNCATE_STDOUT):
        return truncate(to_str(self._stdout).strip(), truncated_to)
    def output_file(self):
        try:
            with tempfile.NamedTemporaryFile(
                dir=TMP_FOLDER, delete=False, suffix=".log", prefix="lambda_"
            ) as f:
                LOG.info(f"writing log to file '{f.name}'")
                f.write(to_bytes(self._stderr))
        except Exception as e:
            LOG.warning("failed to write log to file, error %s", e)
EXECUTOR_LOCAL = LambdaExecutorLocal()
EXECUTOR_CONTAINERS_SEPARATE = LambdaExecutorSeparateContainers()
EXECUTOR_CONTAINERS_REUSE = LambdaExecutorReuseContainers()
DEFAULT_EXECUTOR = EXECUTOR_CONTAINERS_SEPARATE
AVAILABLE_EXECUTORS = {
    "local": EXECUTOR_LOCAL,
    "docker": EXECUTOR_CONTAINERS_SEPARATE,
    "docker-reuse": EXECUTOR_CONTAINERS_REUSE,
}