[test] call sphinx once per tutorial file #4370

Job	Run time
pytorch_tutorial_build_worker (5, 15, linux.g5.4xlarge.nvidia.gpu)	22m 52s
pytorch_tutorial_build_worker (1, 15, linux.g5.12xlarge.nvidia.gpu)	11m 57s
pytorch_tutorial_build_worker (10, 15, linux.g5.4xlarge.nvidia.gpu)	1h 1m 10s
pytorch_tutorial_build_worker (8, 15, linux.g5.4xlarge.nvidia.gpu)	21m 46s
pytorch_tutorial_build_worker (2, 15, linux.g5.4xlarge.nvidia.gpu)	24m 37s
pytorch_tutorial_build_worker (9, 15, linux.g5.4xlarge.nvidia.gpu)	44m 29s
pytorch_tutorial_build_worker (6, 15, linux.g5.4xlarge.nvidia.gpu)	41m 33s
pytorch_tutorial_build_worker (3, 15, linux.g5.4xlarge.nvidia.gpu)	21m 10s
pytorch_tutorial_build_worker (4, 15, linux.g5.4xlarge.nvidia.gpu)	30m 55s
pytorch_tutorial_build_worker (7, 15, linux.g5.4xlarge.nvidia.gpu)	29m 36s
pytorch_tutorial_build_worker (11, 15, linux.g5.4xlarge.nvidia.gpu)	14m 8s
pytorch_tutorial_build_worker (12, 15, linux.g5.4xlarge.nvidia.gpu)	1h 5m 2s
pytorch_tutorial_build_worker (15, 15, linux.g5.4xlarge.nvidia.gpu)	1h 12m 59s
pytorch_tutorial_build_worker (13, 15, linux.g5.4xlarge.nvidia.gpu)	13m 18s
pytorch_tutorial_build_worker (14, 15, linux.g5.4xlarge.nvidia.gpu)	1h 13m 13s
pytorch_tutorial_build_manager	0s
	9h 8m 45s

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