make sure gc_steps is used for all trainers (axolotl-ai-cloud#2638)

Author: winglian

src/axolotl/core/trainer_builder.py

@@ -168,6 +168,9 @@ def get_callbacks(self) -> List[TrainerCallback]:
                 )
             )
 
+        if self.cfg.gc_steps:
+            callbacks.append(GCCallback(gc_steps=self.cfg.gc_steps))
+
         if self.cfg.use_wandb:
             callbacks.append(
                 SaveAxolotlConfigtoWandBCallback(self.cfg.axolotl_config_path)
@@ -249,9 +252,6 @@ def get_callbacks(self):
         if self.cfg.loss_watchdog_threshold is not None:
             callbacks.append(LossWatchDogCallback(self.cfg))
 
-        if self.cfg.gc_steps:
-            callbacks.append(GCCallback(gc_steps=self.cfg.gc_steps))
-
         return callbacks
 
     def get_post_trainer_create_callbacks(self, trainer):