### 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["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
            environment["AWS_LAMBDA_FUNCTION_MEMORY_SIZE"] = str(context.memory_limit_in_mb)
        
        queue = Queue()
        lambda_function_callable = self.get_lambda_callable(
            lambda_function, qualifier=inv_context.function_version
        )
        def do_execute():
            
            result = None
            try:
                if lambda_cwd:
                    os.chdir(lambda_cwd)
                    sys.path.insert(0, "")
                if environment:
                    os.environ.update(environment)
                
                self.set_default_env_variables()
                
                result = lambda_function_callable(inv_context.event, context)
            except Exception as e:
                result = str(e)
                sys.stderr.write("%s %s" % (e, traceback.format_exc()))
                raise
            finally:
                queue.put(result)
        process = Process(target=do_execute)
        start_time = now(millis=True)