Do not share VirtualDeviceImpl lock with SensorController

There's no reason to share those locks and separating the locks breaks
lock inversion cycle.

Also, return copy of mSensorDescriptors in getSensorDescriptors instead
of original map.

Bug: 278900649
Test: atest CtsVirtualDevicesTestCases
Change-Id: I993ae4f0c2a5590529bcabaa15463956b3aa5b1d