### 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_
alias_name = f"test_alias_{short_uid()}"
        create_result = create_lambda_function(
            func_name=func_name,
            handler_file=TEST_LAMBDA_INTROSPECT_PYTHON,
            runtime=LAMBDA_RUNTIME_PYTHON38,
            client=lambda_client,
            timeout=2,
        )
        snapshot.match("create-result", create_result)
        fn = lambda_client.get_function_configuration(FunctionName=func_name, Qualifier="$LATEST")
        snapshot.match("get-function-configuration", fn)
        assert fn["State"] == "Active"
        first_ver = lambda_client.publish_version(
            FunctionName=func_name, RevisionId=fn["RevisionId"], Description="my-first-version"
        )
        snapshot.match("publish_version_1", first_ver)
        assert first_ver["State"] == "Active"
        assert fn["RevisionId"] != first_ver["RevisionId"]
        get_function_configuration = lambda_client.get_function_configuration(
            FunctionName=func_name, Qualifier=first_ver["Version"]
        )
        snapshot.match("get_function_configuration_version_1", first_ver)
        assert get_function_configuration["RevisionId"] == first_ver["RevisionId"]
        # There's no ProvisionedConcurrencyConfiguration yet
        assert get_invoke_init_type(lambda_client, func_name, first_ver["Version"]) == "on-demand"
        # Create Alias and add ProvisionedConcurrencyConfiguration to it
        alias = lambda_client.create_alias(
            FunctionName=func_name, FunctionVersion=first_ver["Version"], Name=alias_name
        )
        snapshot.match("create_alias", alias)