RepositoryServlet should not register the repository when started with repo.verify.configuration=true

The (Enterprise) Configuration Verifier requires starting the repository with system parameter -Drepo.verify.configuration=true, which thereafter should not be used.

The current logic in the RepositoryServlet however always registers the created repository instance in the HippoServiceRegistry, thereby allowing other usages (typically triggered immediately when using a ServiceTracker).

That logic (to register the repository instance) must be made conditional, to be skipped in case of repo.verify.configuration=true.