gpo: Improve debug messages
    
    Improve debug messages during security filtering. It was not possible
    to figure out why the GPO was filtered by reading the logs, because
    we use the same debug message in various cases.
    
    Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>
    (cherry picked from commit 47680083e7e4bf5c433657171bf84cceacc83339)
    (cherry picked from commit 9bf6c4b5afb5054282f7b8c4c5f7bed26a259f5a)