Fix a regression in FullyShardedDataParallelPlugin.set auto wrap policy : transformer-based auto-wrapping…

Fix a regression in FullyShardedDataParallelPlugin.set auto wrap policy : transformer-based auto-wrapping…: a task in HF ML Tasksmith (Harbor dataset). Example that must work: a model with no split modules = "MyTransformerBlock" passed to set auto wrap policy with transformer cls names to…