floss: Refactor BAS disconnection on profiles disconnection

Previously (observed in guest mode),
1. A HID device would connect via Fastpair
2. We would try to connect HID
3. Fastpair would disconnect its GATT connection
4. Since HID hasn't been fully connected, BAS thinks there are no more
        active connections and disconnects

This change avoids disconnecting BAS if HID is connecting.

Bug: 386151370
Tag: #floss
Test: m -j
Test: Connect to a HID device via Fastpair in guest mode. Observe
        battery level is visible
Test: Connect to an LE HID device. Observe battery level is visible
Flag: EXEMPT, Floss-only change

Change-Id: I74258fdf427d6264e5487aec3b2eb1bb713f3081