Floss: Report device disconnect only when both transports disconnected

Previously, Floss reported disconnection upon any single transport disconnect.
This caused issues when devices (like Largo) utilized both BR/EDR and GATT, as GATT disconnects
were misinterpreted as full device disconnections.

This change introduces separate link state tracking for BR/EDR and LE. Disconnection is now
reported only when both transports are confirmed disconnected.

Bug: 341234108
Test: run bluetooth_AdapterLEHealth, bluetooth_AdapterCLHealth,
bluetooth_AdapterSRHealth, bluetooth_AdalterMDHealth
Test: m Bluetooth
Flag: EXEMPT floss only changes

Change-Id: I43320ad37f9dbc7e4e84cb1ac261df0f279f1f85