1. Clear connected Bluetooth device from preference when Bluetooth state
is off.
2. Do not force to update the list of Bluetooth device when Bluetooth is
disable.
3. Add test to verify following situations:
1. Do not force to update the list of Bluetooth device when Bluetooth
is disable.
2. Force to update the list of Bluetooth device when Bluetooth is
enable.
3. Force to update the list of Bluetooth device when Bluetooth state
is on.
4. Clear the connected Bluetooth device from preference when
Bluetooth state is off.
Bug: 110178164
Test: make -j42 RunSettingsRoboTests
Change-Id: I8b17c5d761e010e4eab620355c8b9185543e85ed
8ee474a369