errors during initial bootstrap can result in multiple hcm:hcm nodes

The flow of detecting this run is the "first" bootstrap in combination with creating the hcm:hcm node is not correct yet. Below a reproduction path that resulted in multiple root hcm:hcm nodes. Note that if in another issue we remove the capability to have sns on root, we should validate these steps; most likely when starting the project for the second time it will try and add the hcm:hcm node and fail as sns are no longer supported.

• generate a Hippo project
• patch the Repository: in org.onehippo.cm.engine.ConfigurationConfigService#computeAndWriteDelta, throw a RuntimeException (see attached patch)
• rebuild the project, start it, wait for Tomcat to complete the startup (you will see the RuntimeException in the console)
• remove the patch, rebuild and restart
• open the console, you now have 2 hcm:hcm nodes in the root of the repository