### 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_
try:
        import xml.etree.ElementTree as et
        import requests
        response = requests.get(metadata_url)
        xml = et.fromstring(response.content)
        latest_version = xml.find("./versioning/latest").text
        return latest_version
    except Exception as e:
        print("Unable to get latest version of Thundra Java agent: %s" % e)
        return "LATEST"
def _init_java_agent_configs():
    global THUNDRA_JAVA_AGENT_REMOTE_URL
    global THUNDRA_JAVA_AGENT_LOCAL_PATH
    metadata_url = (
        "https://repo.thundra.io/service/local/repositories/thundra-releases/content/"
        + "io/thundra/agent/thundra-agent-lambda-bootstrap/maven-metadata.xml"
    )
    latest_version = _get_latest_java_agent_version(metadata_url)
    version = os.getenv("THUNDRA_AGENT_JAVA_VERSION", latest_version)
    jar_name = "thundra-agent-%s.jar" % version
    THUNDRA_JAVA_AGENT_REMOTE_URL = (
        "https://repo.thundra.io/service/local/artifact/maven/redirect?"
        + "r=thundra-releases&g=io.thundra.agent&a=thundra-agent-lambda-bootstrap&v={v}"
    ).format(v=version)
    THUNDRA_JAVA_AGENT_LOCAL_PATH = "%s/%s" % (config.dirs.tmp, jar_name)
def _install_java_agent():