Remove usage and configurability of /hippo:security/hipposys:*path properties

The /hippo:configuration/hippo:security node provides and requires the following (mandatory!) path properties, as defined in its node type hipposys:securityfolder:

• hipposys:userspath (string) mandatory
  default value: "hippo:configuration/hippo:users"
• hipposys:groupspath (string) mandatory
  default value: "hippo:configuration/hippo:groups"
• hipposys:rolespath (string) mandatory
  default value: "hippo:configuration/hippo:roles"
• hipposys:domainspath (string) mandatory
• default value: "hippo:configuration/hippo:domains"

Actually, the last one, hipposys:domainspath, just has been made obsolete and optional as needed for REPO-2242.

For the other configurable path properties none in practice are every changed (or extremely unlikely so), because:

1. There simply is no point/purpose of moving any of these, e.g. moving the users, groups, roles (and new: userroles) folder elsewhere.
2.  Our default (bootstrap) configuration is obviously unable to take this into account, so regardless would remain 'seeding' the default folders, anyway. Making it practically unfeasible for projects to use a different location for any of these.

So this is a theoretical flexibility which serves no purpose, and is awkward in the application code needing to cater for such potential, but never used, customization.

As we're heavily restructuring the whole of the security configuration already, and this would be a change will little/zero chance of impacting exiting projects, this is the time to drop this 'flexibility' by:

• making these properties in the hipposys:securityfolder nodetype optional (and marking/commenting them to be obsolete)
• removing the default configuration value bootstrapped through the configuration.yaml in the repository engine module
• adjusting and cleaning up the code to just take the default value now as a constant

Note again: the above changes already have been done for the domainsPath property through REPO-2242.