### 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_
assert "requestId" in payload
        else:
            assert "requestId" not in payload
parametrize_node_runtimes = pytest.mark.parametrize(
    "runtime",
    NODE_TEST_RUNTIMES,
)
class TestNodeJSRuntimes:
    @pytest.mark.skipif(
        not use_docker(), reason="Test for docker nodejs runtimes not applicable if run locally"
    )
    @parametrize_node_runtimes
    @pytest.mark.skip_snapshot_verify
    def test_nodejs_lambda_with_context(
        self, lambda_client, create_lambda_function, runtime, check_lambda_logs, snapshot
    ):
        """Test context of nodejs lambda invocation"""
        snapshot.add_transformer(snapshot.transform.lambda_api())
        function_name = f"test-function-{short_uid()}"
        creation_response = create_lambda_function(
            func_name=function_name,
            handler_file=TEST_LAMBDA_INTEGRATION_NODEJS,
            handler="lambda_integration.handler",
            runtime=runtime,
        )
        snapshot.match("creation", creation_response)
        ctx = {
            "custom": {"foo": "bar"},
            "client": {"snap": ["crackle", "pop"]},
            "env": {"fizz": "buzz"},