In the vulkan we track the device buffers in the TrackedObjectsVK. This is superfluous since those objects are maintained by the HostBuffer. We should rely on the HostBuffer to keep them alive instead of spending the extra cycles bumping shared_ptr references and hashing. The one exception is that if a buffer is requested that is too large for the HostBuffer, that will have to be tracked.

cc @jonahwilliams