pt: let pt_util create the groups it wants

pt: let pt_util create the groups it wants

if you are rebuilding from pt_util, data sanitization should
not randomly chown and/or rename your groups. likewise,
an admin should have the ability to do this.

Change-Id: Id76cd16acc4af712b9be6d0c7110e8db10ce3fff
Reviewed-on: http://gerrit.openafs.org/9841
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>