camera-vts: don't import gralloc buffer after allocating

Before moving to GraphicBufferAllocator, the test just allocated
the buffer. GraphicBufferAllocator allocates and imports the buffer.
Update the test to only allocate the buffer.

Bug: 145941038
Test: VtsHalCameraProviderV2_4TargetTest

Change-Id: Ib3801d06265836eec2875f13ae6f2ec070d7d353
1 file changed