[Backport release-25.05] buildPython*: unconditionally add .override (#455389)

pkgs/development/interpreters/python/python-packages-base.nix

@@ -39,7 +39,7 @@ let
       else
         result
     )
-    // lib.optionalAttrs (f ? override) {
+    // {
       # Support overriding `f` itself, e.g. `buildPythonPackage.override { }`.
       # Ensure `makeOverridablePythonPackage` is applied to the result.
       override = lib.mirrorFunctionArgs f.override (fdrv: makeOverridablePythonPackage (f.override fdrv));