python:gp: Do not print an error if template already exists

python:gp: Do not print an error if template already exists

We will get an exit status for duplicate in future:
https://www.pagure.io/certmonger/issue/269
We can't really fix that right now, as older version of certmonger
don't support the `-v` option.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15559

Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: David Mulder <dmulder@samba.org>
Reviewed-by: Pavel Filipenský <pfilipensky@samba.org>