Hide the "remove GPU after training" button.

Training of a LoRA DreamBooth model often only takes about 10 minutes
and this feature is not very useful for this Space.

app_training.py

@@ -95,7 +95,8 @@ def create_training_demo(trainer: Trainer,
         remove_gpu_after_training = gr.Checkbox(
             label='Remove GPU after training',
             value=False,
-            interactive=bool(os.getenv('SPACE_ID')))
+            interactive=bool(os.getenv('SPACE_ID')),
+            visible=False)
         run_button = gr.Button('Start Training')
 
         with gr.Box():