### Is there an existing issue for this?

- [X] I have searched the existing issues and read the documentation

### Question

A [recent commit](https://github.com/localstack/localstack/commit/f41b25cc8d68e97ce8eacd4374ded4a8072e50f6#diff-368e25a43c4a3200ecb9ae21e7b2a94da05d8eb24680bd6c2a37ee0e275bcd0aL67) scrapped the `{"features:initScripts":"initialized"}` feature that my team was relying on to bootstrap our development environment.

Basically we are putting a provisioning script in `/docker-entrypoint-initaws.d/` that installs Terraform and runs our Terraform definitions against `http://localhost:4566`. Then, the service that needs the AWS infrastructure has an entrypoint that polls `http://localstack:4566/health` and keeps looking for `{"features:initScripts":"initialized"}` in the response before attempting to actually start the service.

We found by trial and error that this was the most reliable way to bring up our stack, as opposed to looking for specific services to appear in the `/health` payload. However, now with this change we can't detect exactly when our Terraform provisioning finishes. It'd be great to get back that feature, or to have another way to detect when the LocalStack entrypoint has finished running the scripts in `/docker-entrypoint-initaws.d/`. For now we'll be sticking to `:0.12.19` instead of `:latest` as suggested.

Thank you.

### Anything else?

_No response_
cls = super(moto_core.models.InstanceTrackerMeta, meta).__new__(meta, name, bases, dct)
        if name == "BaseModel":
            return cls
        cls.instances = []
        return cls
    moto_core.models.InstanceTrackerMeta.__new__ = new_intance
    def new_basemodel(cls, *args, **kwargs):
        instance = super(moto_core.models.BaseModel, cls).__new__(cls)
        return instance
    moto_core.models.BaseModel.__new__ = new_basemodel
def get_multiserver_or_free_service_port():
    if config.FORWARD_EDGE_INMEM:
        return multiserver.get_moto_server_port()
    return get_free_tcp_port()
def register_signal_handlers():
    global SIGNAL_HANDLERS_SETUP
    if SIGNAL_HANDLERS_SETUP:
        return
    
    def signal_handler(sig, frame):
        LOG.debug("[shutdown] signal received %s", sig)
        stop_infra()
        if config.FORCE_SHUTDOWN:
            sys.exit(0)
    signal.signal(signal.SIGTERM, signal_handler)
    signal.signal(signal.SIGINT, signal_handler)
    SIGNAL_HANDLERS_SETUP = True
def do_run(