Don't autosave unmodified buffers (#32626)

Closes https://github.com/zed-industries/zed/issues/12091

Proper redo of https://github.com/zed-industries/zed/pull/32603

Release Notes:

- Fixed formatting effects not triggered when saving unmodified
singleton buffers

---------

Co-authored-by: Max Brunsfeld <maxbrunsfeld@gmail.com>
Co-authored-by: Cole Miller <m@cole-miller.net>

assets/settings/default.json

@@ -219,9 +219,6 @@
   "inline_code_actions": true,
   // Whether to allow drag and drop text selection in buffer.
   "drag_and_drop_selection": true,
-  // Whether to save singleton buffers that are not dirty.
-  // This will "touch" the file and related tools enabled, e.g. formatters.
-  "save_non_dirty_buffers": true,
   // What to do when go to definition yields no results.
   //
   // 1. Do nothing: `none`