Make benchmark for training work with multiple gpus
Make benchmark for training work with multiple gpus

Summary:
1. For tensorboard_trace_handler, ``worker_name`` should be unique for each worker in distributed scenario.
2. Turn off saving `profiler-trace-iter{}.json` in the output dir when `save_tensorboard=True` as it seems like we cannot have both enabled right now (discussions are here https://fb.workplace.com/groups/289111155699012/permalink/640990860511038/)

Reviewed By: ppwwyyxx

Differential Revision: D31312437

fbshipit-source-id: b50d80c9f288a35483d9a41ce07e0307c15c297f

facebookresearch/detectron2,facebookresearch/detectron2,facebookresearch/detectron2