Questions about ingester and object storage

Hi, I am currently using the single-node mode of Pyrosope and Minio S3 storage for monitoring, and I have encountered a few issues during the process.

- Does the single-node mode supports directly querying historical messages from S3 now #2045 ? Can the cluster mode do this as well?
- Regarding the upload policy to S3 storage, the [documentation](https://grafana.com/docs/pyroscope/next/configure-server/configure-object-storage-backend/) only mentions that it will be saved locally before uploading. I would like to know the specific upload policy, such as whether it is done periodically

I try to use filesystem as the long-term storage for Pyroscope, here is my config
```yaml
server:
http_listen_port: 4040

storage:
backend: filesystem
filesystem:
dir: "/testdata"

scrape_configs:
- job_name: "default"
scrape_interval: "15s"
static_configs:
- targets: ["127.0.0.1:4040"]
labels:
service_name: "pyroscope"
```
And i set the `--pyroscopedb.max-block-duration=5m` for test. I already running the server for about 1 hour, but i cannot any blocks in my `/testdata` directory