### 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_
TMP_FILES.append(event_file)
        classpath = "%s:%s:%s" % (
            main_file,
            Util.get_java_classpath(main_file),
            LAMBDA_EXECUTOR_JAR,
        )
        cmd = "java %s -cp %s %s %s" % (
            java_opts,
            classpath,
            LAMBDA_EXECUTOR_CLASS,
            event_file,
        )
        
        inv_context = InvocationContext(
            lambda_function, event, environment=lambda_function.envvars, lambda_command=cmd
        )
        result = self.apply_plugin_patches(inv_context)
        if isinstance(result, InvocationResult):
            return result
        cmd = inv_context.lambda_command
        LOG.info(cmd)
        
        invocation_result = self._execute_in_custom_runtime(cmd, lambda_function=lambda_function)
        return invocation_result
    def execute_javascript_lambda(
        self, event, context, main_file, lambda_function: LambdaFunction = None
    ):
        handler = lambda_function.handler
        function = handler.split(".")[-1]
        event_json_string = "%s" % (json.dumps(json_safe(event)) if event else "{}")