GPU utilization not showing on MIG devices

It was discovered while reviewing #8693 that GPUs partitioned with MIG do not support showing their utilization.

In #8693 I pushed a fix so that instead of getting an error when reading the utilization the graphs just show zero. But we may want to explore a longer term solution to getting MIG utilization.

The [NVML documentation states that utilization querying isn't supported on MIG](https://docs.nvidia.com/deploy/nvml-api/group__nvmlDeviceQueries.html#group__nvmlDeviceQueries_1g540824faa6cef45500e0d1dc2f50b321), and as far as I can see there is no alternative. If this is the case and it's not possible at all we may want to think about how we can communicate that to the user rather than just showing an empty graph.