### 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_
"items": [{"id": k, "data": v} for k, v in data.items()],
        }
        def wait_for_table_created():
            return (
                dynamodb_client.describe_table(TableName=table_name)["Table"]["TableStatus"]
                == "ACTIVE"
            )
        assert poll_condition(wait_for_table_created, timeout=30)
        lambda_client.invoke(FunctionName=function_name, Payload=json.dumps(event))
        rs = dynamodb_resource.Table(table_name).scan()
        items = rs["Items"]
        assert len(items) == len(data.keys())
        for item in items:
            assert data[item["id"]] == item["data"]
    @parametrize_python_runtimes
    def test_lambda_start_stepfunctions_execution(
        self, lambda_client, stepfunctions_client, create_lambda_function, runtime, lambda_su_role
    ):
        """Start stepfunctions machine execution from lambda"""
        function_name = f"test-function-{short_uid()}"
        resource_lambda_name = f"test-resource-{short_uid()}"
        state_machine_name = f"state-machine-{short_uid()}"
        create_lambda_function(
            handler_file=TEST_LAMBDA_START_EXECUTION_FILE,
            func_name=function_name,
            runtime=runtime,
            role=lambda_su_role,
        )
        resource_lambda_arn = create_lambda_function(
            handler_file=TEST_LAMBDA_PYTHON_ECHO,