### 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_
assert alias["FunctionVersion"] == first_ver["Version"]
        assert alias["RevisionId"] != first_ver["RevisionId"]
        get_function_result = lambda_client.get_function(
            FunctionName=func_name, Qualifier=first_ver["Version"]
        )
        versioned_revision_id_before = get_function_result["Configuration"]["RevisionId"]
        snapshot.match("get_function_before_provisioned", get_function_result)
        lambda_client.put_provisioned_concurrency_config(
            FunctionName=func_name, Qualifier=alias_name, ProvisionedConcurrentExecutions=1
        )
        assert wait_until(concurrency_update_done(lambda_client, func_name, alias_name))
        get_function_result = lambda_client.get_function(
            FunctionName=func_name, Qualifier=alias_name
        )
        snapshot.match("get_function_after_provisioned", get_function_result)
        versioned_revision_id_after = get_function_result["Configuration"]["RevisionId"]
        assert versioned_revision_id_before != versioned_revision_id_after
        # Alias AND Version now both use provisioned-concurrency (!)
        assert (
            get_invoke_init_type(lambda_client, func_name, first_ver["Version"])
            == "provisioned-concurrency"
        )
        assert (
            get_invoke_init_type(lambda_client, func_name, alias_name) == "provisioned-concurrency"
        )
        # Update lambda configuration and publish new version
        lambda_client.update_function_configuration(FunctionName=func_name, Timeout=10)
        assert wait_until(update_done(lambda_client, func_name))
        lambda_conf = lambda_client.get_function_configuration(FunctionName=func_name)
        snapshot.match("get_function_after_update", lambda_conf)