Fix FSDP2 params and add test

Author: amanzoni1

src/transformers/training_args.py

@@ -2773,7 +2773,6 @@ def _process_fsdp_args(self):
                 # to unexpected behaviour during training, thus throwing error here to prevent it.
                 raise ValueError('`sync_module_states` must be `"True"` if `cpu_ram_efficient_loading` is `"True"`')
 
-
             # we need to set the env here as otherwise we get a warning in accelerate + we need to set it for transformers
             fsdp_plugin_args["cpu_ram_efficient_loading"] = str_to_bool(cpu_ram_efficient_loading)
             os.environ["FSDP_CPU_RAM_EFFICIENT_LOADING"] = cpu_ram_efficient_loading