There is a specific section in the upgrade guide for authentication. There is no config xml files in crx3. All the necessary available config if any should be in felix console.
The parameter does not make sense in AEM6 because
Cluster is recommemded to do it Mongo & AEM does not use tar journal in crx3. CRX3 cluster with tarmk is not possible & supported. If you are using AEM6 with crx 2 still you will still have xml file and can change there.
This can be configured in the Felix console under ‘Apache Jackrabbit Oak AuthorizableActionProvider’ configuration.