fix(Core/AI): Add back leash update. (#19916)

Init.

src/server/game/Entities/Unit/Unit.cpp

@@ -13542,6 +13542,9 @@ void Unit::SetInCombatWith(Unit* enemy, uint32 duration)
         }
     }
 
+    if (Creature* pCreature = ToCreature())
+        pCreature->UpdateLeashExtensionTime();
+
     SetInCombatState(false, enemy, duration);
 }