Cleanup: Don't recalculate normals in versioning code

Normals are not read from files anymore, calculating them in versioning
is unnecessary and wasteful.

source/blender/blenloader/intern/versioning_280.c

@@ -1620,11 +1620,6 @@ void do_versions_after_linking_280(Main *bmain, ReportList *UNUSED(reports))
 
       /* Deprecated, only kept for conversion. */
       BKE_mesh_tessface_clear(me);
-
-      /* Moved from do_versions because we need updated polygons for calculating normals. */
-      if (!MAIN_VERSION_ATLEAST(bmain, 256, 6)) {
-        BKE_mesh_calc_normals(me);
-      }
     }
   }