[CUDA] fix CUDA memory error by reducing block number (fixed #4315) (#4327)
[CUDA] fix CUDA memory error by reducing block number (fixed #4315) (#4327)


microsoft/LightGBM,henry0312/LightGBM,henry0312/LightGBM,henry0312/LightGBM,microsoft/LightGBM,microsoft/LightGBM,henry0312/LightGBM,henry0312/LightGBM,microsoft/LightGBM,microsoft/LightGBM