AdapterService: Handle snoop settings changes

Allow a user to toggle Bluetooth to start or stop snoop logging after
changing the developer setting.

Bug: 67634644
Test: runtest bluetooth \
        -c com.android.bluetooth.btservice.AdapterServiceTest \
        -m testSnoopLoggingChange
Change-Id: Ie42b9485538b6bb679831ba1f8e5eddd50060e13