Fix #133751: Render pass warning with GPU device

`compositor_is_in_use` sets `used_by_compositor` true when GPU device is
selected. This draws render pass warning even when viewport
compositor is disabled. Remove the condition to fix the unintentional
warning. Following function is just used in node drawing, seems safe to
remove then.

Pull Request: https://projects.blender.org/blender/blender/pulls/133753

source/blender/editors/space_node/node_draw.cc

@@ -4833,10 +4833,6 @@ static bool compositor_is_in_use(const bContext &context)
     return false;
   }
 
-  if (scene->r.compositor_device == SCE_COMPOSITOR_DEVICE_GPU) {
-    return true;
-  }
-
   wmWindowManager *wm = CTX_wm_manager(&context);
   LISTBASE_FOREACH (const wmWindow *, win, &wm->windows) {
     const bScreen *screen = WM_window_get_active_screen(win);