Camera: VTS: Don't access invalid resources

There is no guarantee that the static metadata
pointer passed in the "DeviceCb" contructor will
be valid after the call completes.  The device
callback instance is expected to be active until
the camera session is open. Clone the required
metadata in "DeviceCb" and manage the lifetime
appropriately by using the "CameraMetadata"
wrapper.

Bug: 135976837
Test: CameraHidlTest#processCaptureRequestPreview
Change-Id: Idd3c6c8c2e5a3fc44a49712e25a04009cbd471b1