fix(Scripts/PitOfSauron): Reset Scourgelord Tyrannus encounter state (#21057)

Co-authored-by: Nicholas Lee <nicholaslee@Nicholass-MacBook-Air.local>
Co-authored-by: blinkysc <binders-36-gap@icloud.com>

src/server/scripts/Northrend/FrozenHalls/PitOfSaron/boss_scourgelord_tyrannus.cpp

@@ -97,6 +97,7 @@ public:
                     if (Vehicle* v = c->GetVehicleKit())
                         v->InstallAllAccessories(false);
                 }
+                pInstance->SetData(DATA_TYRANNUS, NOT_STARTED);
             }
         }