Safely end training even if trackers weren't initialized (#1994)

* Update accelerator.py

* init trackers on class init

* dont need getattr because trackers exists

src/accelerate/accelerator.py

@@ -264,6 +264,7 @@ def __init__(
         kwargs_handlers: list[KwargsHandler] | None = None,
         dynamo_backend: DynamoBackend | str | None = None,
     ):
+        self.trackers = []
         if project_config is not None:
             self.project_configuration = project_config
         else:
@@ -2399,7 +2400,6 @@ def init_trackers(self, project_name: str, config: dict | None = None, init_kwar
         ... )
         ```
         """
-        self.trackers = []
         for tracker in self.log_with:
             if issubclass(type(tracker), GeneralTracker):
                 # Custom trackers are already initialized
@@ -2441,7 +2441,7 @@ def get_tracker(self, name: str, unwrap: bool = False):
         >>> tensorboard_tracker = accelerator.get_tracker("tensorboard")
         ```
         """
-        if len(getattr(self, "trackers", [])) > 0:
+        if len(self.trackers) > 0:
             for tracker in self.trackers:
                 if tracker.name == name:
                     return tracker.tracker if unwrap else tracker