## What changed?
- Check all non-drained version queues before marking a partition
drained.
- Scaler Describe calls only inspect loaded partitions and do not
refresh queue liveness.
## Why?
- `AllActive` missed unloaded per-version backlog
- Loading unloaded partitions from the scaler caused reload cycles.
## How did you test it?
- [ ] built
- [ ] run locally and tested manually
- [x] covered by existing tests
- [x] added new unit test(s)
- [ ] added new functional test(s)
## Potential risks
Scale-down may wait until an unloaded partition is loaded by real
traffic. Explicit version queues may still be loaded when their
partition is already loaded.
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