[BT LE unicast] clear the GroupId when user click 'Forget'

- To clear the groupId after device unpaired.
- switchMemberDeviceContent don't change the member list.

Bug: 240103816
Test: build pass.
[pass] make RunSettingsLibRoboTests -j40 ROBOTEST_FILTER=CachedBluetoothDeviceManagerTest
[psss] make RunSettingsLibRoboTests -j40 ROBOTEST_FILTER=CachedBluetoothDeviceTest

Change-Id: I65dc254f33236fa7fad08a07e56187962700e6c6
6 files changed