Fully reload the instance list once the folder is changed

Signed-off-by: Trial97 <alexandru.tripon97@gmail.com>

launcher/InstanceList.cpp

@@ -768,6 +768,9 @@ void InstanceList::on_InstFolderChanged([[maybe_unused]] const Setting& setting,
         }
         m_instDir = newInstDir;
         m_groupsLoaded = false;
+        beginRemoveRows(QModelIndex(), 0, count());
+        m_instances.erase(m_instances.begin(), m_instances.end());
+        endRemoveRows();
         emit instancesChanged();
     }
 }