### 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_
for env_name, env_value in env_vars_before.items():
            env_value_before = env_vars_before.get(env_name)
            os.environ[env_name] = env_value_before or ""
            if env_value_before is None:
                os.environ.pop(env_name, None)
    @classmethod
    def get_lambda_callable(cls, function: LambdaFunction, qualifier: str = None) -> Callable:
        """Returns the function Callable for invoking the given function locally"""
        qualifier = function.get_qualifier_version(qualifier)
        func_dict = cls.FUNCTION_CALLABLES.get(function.arn()) or {}
        
        callable = func_dict.get(qualifier) or func_dict.get(LambdaFunction.QUALIFIER_LATEST)
        if not callable:
            raise Exception(
                f"Unable to find callable for Lambda function {function.arn()} - {qualifier}"
            )
        return callable
    @classmethod
    def add_function_callable(cls, function: LambdaFunction, lambda_handler: Callable):
        """Sets the function Callable for invoking the $LATEST version of the Lambda function."""
        func_dict = cls.FUNCTION_CALLABLES.setdefault(function.arn(), {})
        qualifier = function.get_qualifier_version(LambdaFunction.QUALIFIER_LATEST)
        func_dict[qualifier] = lambda_handler
class Util:
    debug_java_port = False
    @classmethod
    def get_java_opts(cls):