Init JNI in Bluetooth Service not the Bluetooth State machine

Since we can have multiple state machines the right lifecycle management
should be done in the Bluetooth service with start and stop operations.
Otherwise, there could be JNI crashes, due to JNI callbacks before the
JNI is setup.

Bug: b/34681827
Test: Connect device over HFP and make a call
Change-Id: I3ebe9d035511ca830f131d5b09461ecccfcc4672