Remove CudaWorkType

[liujuncheng]

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[github-actions]

Speed stats:

GPU Name: GeForce GTX 1080 

PyTorch resnet50 time: 141.0ms (= 7048.0ms / 50, input_shape=[16, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 128.3ms (= 6415.0ms / 50, input_shape=[16, 3, 224, 224], backward is enabled)
Relative speed: 1.10 (= 141.0ms / 128.3ms)

PyTorch resnet50 time: 83.7ms (= 4183.6ms / 50, input_shape=[8, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 74.5ms (= 3727.1ms / 50, input_shape=[8, 3, 224, 224], backward is enabled)
Relative speed: 1.12 (= 83.7ms / 74.5ms)

PyTorch resnet50 time: 54.9ms (= 2744.2ms / 50, input_shape=[4, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 47.9ms (= 2392.8ms / 50, input_shape=[4, 3, 224, 224], backward is enabled)
Relative speed: 1.15 (= 54.9ms / 47.9ms)

PyTorch resnet50 time: 48.2ms (= 2407.9ms / 50, input_shape=[2, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 42.4ms (= 2118.7ms / 50, input_shape=[2, 3, 224, 224], backward is enabled)
Relative speed: 1.14 (= 48.2ms / 42.4ms)

PyTorch resnet50 time: 43.7ms (= 2183.5ms / 50, input_shape=[1, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 42.6ms (= 2130.6ms / 50, input_shape=[1, 3, 224, 224], backward is enabled)
Relative speed: 1.02 (= 43.7ms / 42.6ms)