### 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_
state_dir: str
    lock: rwlock.RWLockable
    def __init__(self, state_dir: str = None, lock: rwlock.RWLockable = None):
        
        self.state_dir = state_dir
        
        self.lock = lock
class StateSerializer(abc.ABC):
    """A state serializer encapsulates the logic of persisting and loading service state to/from disk."""
    @abc.abstractmethod
    def restore_state(self, context: PersistenceContext):
        """Restore state from the underlying persistence file"""
        pass
    @abc.abstractmethod
    def update_state(self, context: PersistenceContext, request: Request):
        """Update persistence state based on the incoming request"""
        pass
    @abc.abstractmethod
    def is_write_request(self, request: Request) -> bool:
        """Returns whether the given request is a write request that should trigger serialization"""
        return False
    def get_lock_for_request(self, request: Request) -> Optional[rwlock.Lockable]:
        """Returns a lock (or None) that should be used to guard the given request, for concurrency control"""
        return None
    def get_context(self) -> PersistenceContext:
        """Returns the current persistence context"""
        return None
class StateSerializerComposite(StateSerializer):