If the user set to be configured by cloudbase-init is already added,
but no logon session has been created for that user, the profile
registry key does not exist.
As a consequence, the SetUserSSHPublicKeysPlugin fails, as it cannot
retrieve the home directory from the registry key.
Change-Id: I4226a1c08e940717709e65ba932ce15c8ce37aed
Closes-Bug: #1415198