Fix GridFoodCollector yaml (#5134) (#5136)

Co-authored-by: andrewcoh <54679309+andrewcoh@users.noreply.github.com>

config/ppo/FoodCollector.yaml

 behaviors:
-  FoodCollector:
+  GridFoodCollector:
     trainer_type: ppo
     hyperparameters:
       batch_size: 1024