Fix typo that makes cluster verify to ignore hooks

The return from LUVerifyCluster should be True (or equivalent) for pass,
and False (or equivalent) for fail. The HooksCallBack function uses '1'
(= True) when a hook fails, which is exactly the opposite of what we
want - it will make failed hooks to reset the result to success,
overriding actual failures in cluster verify.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: René Nussbaumer <rn@google.com>