Inventory link in sidebar not highlighted when on physical disks tab

Should be an easy fix.

https://console-l2rqcn9lt-oxidecomputer.vercel.app/system/inventory/disks

<img width="602" alt="image" src="https://github.com/oxidecomputer/console/assets/3612203/251220da-2156-4db4-89cc-c3b9fdff8b00">
