gp: Skip site GP list if no site is found

gp: Skip site GP list if no site is found

[MS-GPOL] 3.2.5.1.4 Site Search says if the site
search returns ERROR_NO_SITENAME, the GP site
search should be skipped.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15548

Signed-off-by: David Mulder <dmulder@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>
Autobuild-User(master): Andreas Schneider <asn@cryptomilk.org>
Autobuild-Date(master): Tue Jan 23 11:20:35 UTC 2024 on atb-devel-224

(cherry picked from commit f05b61b4991e7f51bd184d76a79f8b50114a0ff3)