Compositor: Remove Auto Render option

This patch removes the Auto Render option from the compositor. This is
done for the following reason:

- The option didn't really work except in the case of transforming an
  object. So it wasn't really reliable.
- It made little sense to use since the introduction of the Viewport
  Compositor.
- It had a number of UX issues, including the fact that it can't be used
  with animation playback, and the fact that rendering can get in the
  way of the UI depending on the preferences for temporary editors.

Pull Request: https://projects.blender.org/blender/blender/pulls/123132

scripts/startup/bl_ui/space_node.py

@@ -849,9 +849,6 @@ class NODE_PT_quality(bpy.types.Panel):
         col = layout.column()
         col.prop(tree, "use_viewer_border")
 
-        col = layout.column()
-        col.prop(snode, "use_auto_render")
-
 
 class NODE_PT_overlay(Panel):
     bl_space_type = 'NODE_EDITOR'