Migrate to BluetoothStatsLog from StatsLog

As part of statsd becoming a Mainline module in R, autogenerated
StatsLog.write() calls are going away and replaced by *StatsLog.java
that is autogenerated for each module.
This CL adds autogenerated BluetoothlStatsLog and replaces usages
of StatsLog with BluetoothStatsLog.

Bug: 145952197
Test: m Bluetooth
Change-Id: I1b9fcff3c5fff8f20623ecebd53a625502aeb936