Investigate diagmond timing out when trying to open devices after being run for a long time (because of the UDev background task?)

See:

```
[2026-09-26 02:14:08,496] [diagng 1071955] - INFO - connect_usb_intf called on 3-1.2:1.0 (ui/main_window/imp.py:773)
[2026-09-26 02:14:33,520] [diagng 1071955] - ERROR - Failed to open port: GLib.Error('Le délai d’attente est dépassé', 'g-io-error-quark', 24) (ui/main_window/imp.py:784)
```