### 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_
),
            )
            time.sleep(1)
            rs = stepfunctions_client.list_executions(stateMachineArn=sm_arn)
            
            assert 1 == len([ex for ex in rs["executions"] if ex["stateMachineArn"] == sm_arn])
        finally:
            
            stepfunctions_client.delete_state_machine(stateMachineArn=sm_arn)
    @pytest.mark.skipif(
        not use_docker(), reason="Test for docker python runtimes not applicable if run locally"
    )
    @parametrize_python_runtimes
    def test_python_runtime_correct_versions(self, lambda_client, create_lambda_function, runtime):
        """Test different versions of python runtimes to report back the correct python version"""
        function_name = f"test_python_executor_{short_uid()}"
        create_lambda_function(
            func_name=function_name,
            handler_file=TEST_LAMBDA_PYTHON_VERSION,
            runtime=runtime,
        )
        result = lambda_client.invoke(
            FunctionName=function_name,
            Payload=b"{}",
        )
        result = json.loads(to_str(result["Payload"].read()))
        assert result["version"] == runtime
    @pytest.mark.skipif(
        not use_docker(), reason="Test for docker python runtimes not applicable if run locally"
    )