layers: Remove unique_objects ext list generation
layers: Remove unique_objects ext list generation

Change-Id: I9b958f1799f1cab76a69c4de35590745d3e7a852

KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers