fix(Scripts/FireworkShow): set firework gameobjects active (#19403)

- improve visibility of the show
- prevent glitches in the show execution
- each gameobject only exists for a very short duration, so there
  should be no relevant performance impacts

src/server/scripts/Events/firework_show/firework_show.cpp

@@ -178,6 +178,7 @@ struct go_firework_show : public GameObjectAI
             // trigger despawn animation for firework explosion
             if (go)
             {
+                go->setActive(true);
                 go->DespawnOrUnsummon();
                 go->AddObjectToRemoveList();
             }