goldfish-opengl: nuke VirtioGpuStream The VirtioGpuStream was used for the original bring-up of the pipe_virglrenderer. All users have now transitioned to the VirtioGpuPipeStream and virtio ASG. BUG=239639751 TEST=compile Change-Id: Ifae199b3d04bae09ef094f1aa4823e1ac4c49890