test_get_online_features fails on GPU hosts: expected tensor built on cpu

## Expected Behavior

`sdk/python/tests/unit/online_store/test_online_retrieval.py::test_get_online_features` should pass on any host, with or without a CUDA device.

## Current Behavior

On a host with CUDA available, the test fails:

RuntimeError: Expected all tensors to be on the same device, but got other
is on cpu, different from other tensors on cuda:0
(when checking argument in method wrapper_CUDA__equal)

`OnlineResponse.to_tensor()` places its output on `cuda` when a GPU is present (`sdk/python/feast/online_response.py`), but the `avg_orders_day` assertion builds its expected tensor without a `device=` argument, so it stays on `cpu`.

The test already computes `device` and passes it for the `driver_id` and `trips` assertions — only `avg_orders_day` omits it.

## Steps to reproduce

On a machine with CUDA-enabled torch installed:

python -m pytest sdk/python/tests/unit/online_store/test_online_retrieval.py::test_get_online_features

Fails with the GPU visible; passes under `CUDA_VISIBLE_DEVICES=""`. CI is CPU-only, where `device` resolves to `"cpu"` and the omission has no effect.

### Specifications

- Version: master (0.66.0 dev)
- Platform: Ubuntu 24.04 (WSL2), Python 3.11, torch 2.13.0+cu130, RTX 4050
- Subsystem: online store / tests

## Possible Solution

Pass `device=device` to the expected tensor, matching the neighbouring assertions. Submitted as #6777.

Start with sdk/python/tests/unit/online_store/test_online_retrieval.py::test_get_online_features and inspect the neighbouring device-aware tensor assertions. Update the avg_orders_day expected tensor to use the computed device, then run the specified pytest test with and without CUDA visibility to confirm it passes in both environments.

Written by the indexing model from the issue text.