### 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_
func_name=resource_lambda_name,
            runtime=runtime,
            role=lambda_su_role,
        )["CreateFunctionResponse"]["FunctionArn"]
        state_machine_def = {
            "StartAt": "step1",
            "States": {
                "step1": {
                    "Type": "Task",
                    "Resource": resource_lambda_arn,
                    "ResultPath": "$.result_value",
                    "End": True,
                }
            },
        }
        rs = stepfunctions_client.create_state_machine(
            name=state_machine_name,
            definition=json.dumps(state_machine_def),
            roleArn=lambda_su_role,
        )
        sm_arn = rs["stateMachineArn"]
        try:
            lambda_client.invoke(
                FunctionName=function_name,
                Payload=json.dumps(
                    {
                        "state_machine_arn": sm_arn,
                        "region_name": stepfunctions_client.meta.region_name,
                        "input": {},
                    }