### 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_
"""Called once during startup - can be used, e.g., to prepare Lambda Docker environment"""
        pass
    def cleanup(self, arn=None):
        """Called once during startup - can be used, e.g., to clean up left-over Docker containers"""
        pass
    def provide_file_to_lambda(self, local_file: str, inv_context: InvocationContext) -> str:
        """Make the given file available to the Lambda process (e.g., by copying into the container) for the
        given invocation context; Returns the path to the file that will be available to the Lambda handler."""
        raise NotImplementedError
    def apply_plugin_patches(self, inv_context: InvocationContext) -> Optional[InvocationResult]:
        """Loop through the list of plugins, and apply their patches to the invocation context (if applicable)"""
        invocation_results = []
        for plugin in LambdaExecutorPlugin.get_plugins():
            if not plugin.should_apply(inv_context):
                continue
            
            if not hasattr(plugin, "_initialized"):
                LOG.debug("Initializing Lambda executor plugin %s", plugin.__class__)
                plugin.initialize()
                plugin._initialized = True
            
            inv_options = plugin.prepare_invocation(inv_context)
            if not inv_options:
                continue
            if isinstance(inv_options, InvocationResult):
                invocation_results.append(inv_options)
                continue
            
            file_keys_map = {}
            for key, file_path in inv_options.files_to_add.items():