Only call into VirtualDeviceManager if we have one

VirtualDeviceManager will not be instantiated if a device is missing the
feature flag, FEATURE_COMPANION_DEVICE_SETUP. At the moment,
at least cf_x86_tv doesn't have this feature flag, so we add a null check
to make such targets happy again.

Unnecessary global locking in the common case of VibrationSettings
looking up DEFAULT_DISPLAY is also taken out so that calling
isAppOrDisplayOnAnyVirtualDevice in the middle of shouldIgnoreVibration
won't recursively take mLock.

Change-Id: I683109f3065e0208b78ed37b39ad49cfc615201b
Test: atest VibrationSettingsTest
Test: atest VibratorManagerServiceTest
Bug: 189474679
Bug: 244116059