Bluetooth: Cleanup bt_config.xml during BLE Scan

BLE Scan needs to clean up the bt_config.xml periodically so that
new entries could be added to bt_config.xml. Also, there is no
need to add BLE Random bd_addr to the bt_config.xml

CRs-Fixed: 592338
Change-Id: I1c646e61671050fad9b2d571c558cbe9a97a3f09