replaced ghost_swap with team_change in tests

ml-agents/mlagents/trainers/tests/test_simple_rl.py

             keep_checkpoints=1,
             train_model=True,
             load_model=False,
-            ghost_swap=10000,
+            team_change=10000,
             seed=seed,
             meta_curriculum=meta_curriculum,
             multi_gpu=False,

ml-agents/mlagents/trainers/tests/test_trainer_util.py

             keep_checkpoints=keep_checkpoints,
             train_model=train_model,
             load_model=load_model,
-            ghost_swap=100,
+            team_change=100,
             seed=seed,
         )
         trainers = {}
             keep_checkpoints=keep_checkpoints,
             train_model=train_model,
             load_model=load_model,
-            ghost_swap=100,
+            team_change=100,
             seed=seed,
         )
         trainers = {}
     keep_checkpoints = 1
     train_model = True
     load_model = False
-    ghost_swap = 100
+    team_change = 100
     seed = 11
     bad_config = dummy_bad_config
     BrainParametersMock.return_value.brain_name = "testbrain"
             keep_checkpoints=keep_checkpoints,
             train_model=train_model,
             load_model=load_model,
-            ghost_swap=ghost_swap,
+            team_change=team_change,
             seed=seed,
         )
         trainers = {}
             keep_checkpoints=keep_checkpoints,
             train_model=train_model,
             load_model=load_model,
-            ghost_swap=ghost_swap,
+            team_change=team_change,
             seed=seed,
         )
         trainers = {}
             keep_checkpoints=keep_checkpoints,
             train_model=train_model,
             load_model=load_model,
-            ghost_swap=ghost_swap,
+            team_change=team_change,
             seed=seed,
         )
         trainers = {}
         keep_checkpoints=1,
         train_model=True,
         load_model=False,
-        ghost_swap=100,
+        team_change=100,
         seed=42,
     )
     trainer_factory.generate(brain_parameters.brain_name)
         keep_checkpoints=1,
         train_model=True,
         load_model=False,
-        ghost_swap=100,
+        team_change=100,
         seed=42,
     )
     with pytest.raises(TrainerConfigError):