[test] call sphinx once per tutorial file #4417

Job	Run time
pytorch_tutorial_build_worker (2, 15, linux.g5.4xlarge.nvidia.gpu)	1h 31m 19s
pytorch_tutorial_build_worker (1, 15, linux.g5.12xlarge.nvidia.gpu)	15m 15s
pytorch_tutorial_build_worker (5, 15, linux.g5.4xlarge.nvidia.gpu)	22m 8s
pytorch_tutorial_build_worker (8, 15, linux.g5.4xlarge.nvidia.gpu)	1h 0m 7s
pytorch_tutorial_build_worker (7, 15, linux.g5.4xlarge.nvidia.gpu)	34m 55s
pytorch_tutorial_build_worker (10, 15, linux.g5.4xlarge.nvidia.gpu)	56m 13s
pytorch_tutorial_build_worker (4, 15, linux.g5.4xlarge.nvidia.gpu)	32m 35s
pytorch_tutorial_build_worker (6, 15, linux.g5.4xlarge.nvidia.gpu)	46m 20s
pytorch_tutorial_build_worker (9, 15, linux.g5.4xlarge.nvidia.gpu)	49m 2s
pytorch_tutorial_build_worker (13, 15, linux.g5.4xlarge.nvidia.gpu)	1h 2m 28s
pytorch_tutorial_build_worker (3, 15, linux.g5.4xlarge.nvidia.gpu)	21m 21s
pytorch_tutorial_build_worker (15, 15, linux.g5.4xlarge.nvidia.gpu)	1h 13m 44s
pytorch_tutorial_build_worker (11, 15, linux.g5.4xlarge.nvidia.gpu)	50m 54s
pytorch_tutorial_build_worker (14, 15, linux.g5.4xlarge.nvidia.gpu)	1h 1m 54s
pytorch_tutorial_build_worker (12, 15, linux.g5.4xlarge.nvidia.gpu)	1h 0m 35s
pytorch_tutorial_build_manager	21m 18s
	12h 40m 8s

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