### 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_
tmpdir = tmpdir_factory.mktemp("tmp-java-zip")
        zip_lib_dir = os.path.join(tmpdir, "lib")
        zip_jar_path = os.path.join(zip_lib_dir, "test.lambda.jar")
        mkdir(zip_lib_dir)
        cp_r(
            INSTALL_PATH_LOCALSTACK_FAT_JAR,
            os.path.join(zip_lib_dir, "executor.lambda.jar"),
        )
        save_file(zip_jar_path, test_java_jar)
        return testutil.create_zip_file(tmpdir, get_content=True)
    @pytest.fixture(
        params=JAVA_TEST_RUNTIMES,
    )
    def simple_java_lambda(self, create_lambda_function, test_java_zip, request):
        function_name = f"java-test-function-{short_uid()}"
        create_lambda_function(
            func_name=function_name,
            zip_file=test_java_zip,
            runtime=request.param,
            handler="cloud.localstack.sample.LambdaHandler",
        )
        return function_name
    @pytest.mark.skip_snapshot_verify(
        paths=["$..invoke-result.LogResult", "$..invoke-result.Payload"]
    )
    def test_java_runtime(self, lambda_client, simple_java_lambda, snapshot):
        """Tests a simple java lambda invocation"""
        snapshot.add_transformer(snapshot.transform.lambda_api())
        result = lambda_client.invoke(
            FunctionName=simple_java_lambda,