store-gateway: add memory limits

[dimitarvdimitrov]

Description

In an incident, heavy queries from a single user was causing store-gateways to OOM and therefore affecting other users too.

While there is some limiting of series and chunks within the store-gateway, we don't have anything that properly tracks the memory usage per query and enforces a limit.

This should be similar to the memory limits in the MQE

This requires carefully going through the whole read path in the store-gateway and adding memory accounting and likely requires a design doc.