fix(document): don't apply transforms to nested docs when updating already saved doc

Fix #5807

Author: vkarpov15

lib/model.js

@@ -553,7 +553,13 @@ Model.prototype.$__delta = function() {
       value = value.toObject();
       operand(this, where, delta, data, value);
     } else {
-      value = utils.clone(value, {depopulate: 1, _isNested: true});
+      value = utils.clone(value, {
+        depopulate: true,
+        transform: false,
+        virtuals: false,
+        retainKeyOrder: true,
+        _isNested: true
+      });
       operand(this, where, delta, data, value);
     }
   }