Disable replace_sampler_ddp

Summary: Detectron2 and D2 (https://github.com/facebookresearch/d2go/commit/81ab967feb650145d3a5904f20fdddd28be83445)Go use custom sampler, we don't need Lightning to add distributed sampler.

Reviewed By: ananthsub

Differential Revision: D28921092

fbshipit-source-id: ec8f310d0590ed92227935b979d59a06d7fb7a69

tools/lightning_train_net.py

@@ -92,6 +92,7 @@ def get_trainer_params(cfg: CfgNode, num_machines: int, num_processes: int) -> D
         "num_sanity_val_steps": 0,
         "progress_bar_refresh_rate": 10,
         "terminate_on_nan": True,
+        "replace_sampler_ddp": False,
     }
 
 def do_train(