ci: remove duplicate validation DCO in default rule
ci: remove duplicate validation DCO in default rule

removing duplicated validation of DCO from the default
rule.

Signed-off-by: Humble Chirammal <dc8ba7e82a7df22725dedec9b10c7aaab9ec713f@redhat.com>

ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi