MODE-2275 Fixed Schemata caching by the JcrNodeTypeManager, which caused newly registered node types to not be visible as long as they are registered with the same namespace.

if saving the session fails, the other tests will fail regardless of whether the nodetypes have been successfully unregistered or not. This is because the repository is not started/stopped between tests, so there will be "stale" data in the repo which will be found by the other tests.