Upstream lists tensorboard as a utility from tensorflow despite it
being provided by tensorboard to stop pip for deleting it. This
causes python.withPackages collisions between the two.
The stdenvOverrides overlay is used to bring packages forward during
bootstrapping via stdenv.overrides. These packages have already had
the overlays applied to them in the previous boostrapping stage. If
stdenvOverrides is not last in the overlays stack, all remaining
overlays will windup being applied again to these packages.
closes#34086