### 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_
environment["USE_SSL"] = "1"
        
        if not event:
            LOG.info(
                'Empty event body specified for invocation of Lambda "%s"', lambda_function.arn()
            )
            event = {}
        event_body = json.dumps(json_safe(event))
        event_bytes_for_stdin = self.prepare_event(environment, event_body)
        inv_context.event = event_bytes_for_stdin
        Util.inject_endpoints_into_env(environment)
        environment["EDGE_PORT"] = str(config.EDGE_PORT)
        environment[LAMBDA_HANDLER_ENV_VAR_NAME] = handler
        if os.environ.get("HTTP_PROXY"):
            environment["HTTP_PROXY"] = os.environ["HTTP_PROXY"]
        if lambda_function.timeout:
            environment["AWS_LAMBDA_FUNCTION_TIMEOUT"] = str(lambda_function.timeout)
        if context:
            environment["AWS_LAMBDA_FUNCTION_NAME"] = context.function_name
            environment["AWS_LAMBDA_FUNCTION_VERSION"] = context.function_version
            environment["AWS_LAMBDA_FUNCTION_INVOKED_ARN"] = context.invoked_function_arn
            if context.cognito_identity:
                environment["AWS_LAMBDA_COGNITO_IDENTITY"] = json.dumps(context.cognito_identity)
            if context.client_context is not None:
                environment["AWS_LAMBDA_CLIENT_CONTEXT"] = json.dumps(
                    to_str(base64.b64decode(to_bytes(context.client_context)))
                )
        
        if config.LAMBDA_JAVA_OPTS and is_java_lambda(runtime):
            if environment.get("JAVA_TOOL_OPTIONS"):