Fix various dict related pylint warnings
    
    * dict-keys-not-iterating
    * dict-values-not-iterating
    * dict-items-not-iterating
    * dict-iter-method
    
    See: https://pagure.io/freeipa/issue/7758
    Signed-off-by: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>