Core/Auras: Update mount capability aura after all login loading is done

src/server/game/Handlers/CharacterHandler.cpp

@@ -1453,6 +1453,8 @@ void WorldSession::HandlePlayerLogin(LoginQueryHolder const& holder)
 
     m_playerLoading.Clear();
 
+    _player->UpdateMountCapability();
+
     // Handle Login-Achievements (should be handled after loading)
     _player->UpdateCriteria(CriteriaType::Login, 1);