Fix: Remove pre-2.8 function to reevaluate a single object

This function replaced the evaluated mesh with a new one with the given
custom data type mask. That doesn't work in general anymore for a few
reasons: the increased dependence on named attributes (a opposed to
custom data types), and the "all or nothing" approach to reevaluating
the depsgraph. Other objects might depend on the object's evaluated
geometry, so it shouldn't just be replaced.

If this causes a regression, it's likely that the object is missing
an update tag when a mode is entered that requires extra evaluated data.

Fixes #105912

@@ -1354,2 +1353,2 @@
-      Scene *scene_eval = DEG_get_evaluated_scene(depsgraph);
-      Object *ob_src_eval = DEG_get_evaluated_object(depsgraph, ob_src);
+      const Object *ob_eval = DEG_get_evaluated_object(depsgraph, ob_src);
+      const Mesh *me_eval = BKE_object_get_evaluated_mesh(ob_eval);

@@ -1133,3 +1134,3 @@
     }
     else {
-      me_eval = mesh_get_eval_final(depsgraph, scene_eval, ob_eval, &data_masks);
+      me_eval = BKE_object_get_evaluated_mesh(ob_eval);

@@ -1048,3 +1049,3 @@
       }
 
-      return mesh_get_eval_final(depsgraph, scene, ob_eval, &data_masks);
+      return BKE_object_get_evaluated_mesh(ob_eval);