PyAPI: Remove bpy.app.handlers.scene_update

This is routinely mis-used to continuously run scripts,
causing performance problems.

This should be replaced with more specific handlers, or possibly timers.
See: T47811

source/blender/python/intern/bpy_app_handlers.c

@@ -59,8 +59,6 @@ static PyStructSequence_Field app_cb_info_fields[] = {
 	{(char *)"load_post",         (char *)"on loading a new blend file (after)"},
 	{(char *)"save_pre",          (char *)"on saving a blend file (before)"},
 	{(char *)"save_post",         (char *)"on saving a blend file (after)"},
-	{(char *)"scene_update_pre",  (char *)"on updating the scenes data (before)"},
-	{(char *)"scene_update_post", (char *)"on updating the scenes data (after)"},
 	{(char *)"game_pre",          (char *)"on starting the game engine"},
 	{(char *)"game_post",         (char *)"on ending the game engine"},
 	{(char *)"version_update",    (char *)"on ending the versioning code"},