Revert "st-label: Keep labels fully pre-rendered on the GPU"

This reverts commit 96f1d1b08d.

There have been reports of issues around this commit so back out from
it on the stable branch.

See https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/2937

src/st/st-label.c

@@ -294,7 +294,6 @@ st_label_class_init (StLabelClass *klass)
 static void
 st_label_init (StLabel *label)
 {
-  ClutterActor *actor = CLUTTER_ACTOR (label);
   StLabelPrivate *priv;
 
   label->priv = priv = st_label_get_instance_private (label);
@@ -306,10 +305,7 @@ st_label_init (StLabel *label)
   label->priv->shadow_width = -1.;
   label->priv->shadow_height = -1.;
 
-  clutter_actor_add_child (actor, priv->label);
-
-  clutter_actor_set_offscreen_redirect (actor,
-                                        CLUTTER_OFFSCREEN_REDIRECT_ALWAYS);
+  clutter_actor_add_child (CLUTTER_ACTOR (label), priv->label);
 }
 
 /**