Fix cluster verify error on master-ip-setup script

This error does not show up until we exceed the pool of master
candidates and have nodes which are not master candidates.

The background is that we check for master-ip-setup script on master
candidates and expect them not to be on the other nodes. However, we
distribute a default master-ip-script which break this assumption.
Furthermore, there's no reason why the file should just exists on the
master candidates.

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