Cleanup startAdvertising call

AdvertiseManager.startAdvertising no longer sends multiple commands.
Its native counterpart, BleAdvertisingManagerImpl.RegisterAdvertiser,
thanks to better tests, guarantees that it either sends a success or
error callback. Therefore, no additional synchronization is required.

The only cases when the native code can get executed without a callback
are when the controller sends no response, or the bta thread is stuck.
Both of those cases should result in a crash and restart of bluetooth.

This patch also fixes an error, where if a timeout happens, the  error
callback gets called twice.

Bug: 30622771
Test: sl4a ConcurrentBleAdvertising
Change-Id: I72a729f4da2bd8d5d62a81a6f93dbadab088a036