Add anomaly detector for unoptimized bt scanning

This cl detects bt anomaly by using
BluetoothUnoptimizedScanBackgroundTimer. It will report anomaly
if total duration is longer than threshold.

Future cl will hook up the threshold to server side.

Bug: 36921532
Test: RunSettingsRoboTests
Change-Id: I5d6a42b2d2c4fec94387ca59ba8e6a2f3346d047