Disconnect before removing device

Android BT stack would sometimes not wait for the all related links
to be disconnected before removing the bond. Sometimes, an incoming
connection may get established as the device is being removed.

Test: mmm packages/modules/Bluetooth
Flag: com.android.bluetooth.flags.wait_for_disconnect_before_unbond
Bug: 345299390
Bug: 345299969
Change-Id: I9b946db206b9c809ca40c6dfeffe5f3a222d1f27