Set external control to false on VibratorManagerService init

The VibratorManagerService turns off all vibrators during initialization
to handle the scenario where the system server has restarted (e.g. after
being killed by watchdog after a deadlock) but the vibrator hardware was
still performing a previous vibrate command.

This also sets the external control state to false, so the service won't
attemp to vibrate when the hardware is actually set for external
control.

Bug: 197165183
Test: VibratorManagerServiceTest
Change-Id: If4f0df57333fb5863fe9c1e781575634606ee662