MS-PAC: Special case NFS services
The current Linux NFS server is severely limited when it comes to handling
kerberos tickets. Bsically any ticket bigger than 2k will cause it to fail
authentication due to kernel->userspace upcall interface restrictions.
Until we have additional support in IPA to indivdually mark principals to
opt out of getting PACs attached we always prevent PACs from being attached
to TGTs or Tickets where NFS is involved.