[test] call sphinx once per tutorial file #4355

Job	Run time
pytorch_tutorial_build_worker (2, 15, linux.g5.4xlarge.nvidia.gpu)	37m 52s
pytorch_tutorial_build_worker (1, 15, linux.g5.12xlarge.nvidia.gpu)	15m 12s
pytorch_tutorial_build_worker (8, 15, linux.g5.4xlarge.nvidia.gpu)	26m 56s
pytorch_tutorial_build_worker (4, 15, linux.g5.4xlarge.nvidia.gpu)	35m 23s
pytorch_tutorial_build_worker (9, 15, linux.g5.4xlarge.nvidia.gpu)	17m 56s
pytorch_tutorial_build_worker (6, 15, linux.g5.4xlarge.nvidia.gpu)	22m 23s
pytorch_tutorial_build_worker (3, 15, linux.g5.4xlarge.nvidia.gpu)	21m 52s
pytorch_tutorial_build_worker (10, 15, linux.g5.4xlarge.nvidia.gpu)	16m 12s
pytorch_tutorial_build_worker (5, 15, linux.g5.4xlarge.nvidia.gpu)	23m 15s
pytorch_tutorial_build_worker (7, 15, linux.g5.4xlarge.nvidia.gpu)	19m 52s
pytorch_tutorial_build_worker (11, 15, linux.g5.4xlarge.nvidia.gpu)	15m 32s
pytorch_tutorial_build_worker (12, 15, linux.g5.4xlarge.nvidia.gpu)	20m 45s
pytorch_tutorial_build_worker (15, 15, linux.g5.4xlarge.nvidia.gpu)	27m 47s
pytorch_tutorial_build_worker (13, 15, linux.g5.4xlarge.nvidia.gpu)	29m 28s
pytorch_tutorial_build_worker (14, 15, linux.g5.4xlarge.nvidia.gpu)	26m 35s
pytorch_tutorial_build_manager	23m 21s
	6h 20m 21s

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