ONTAP 9.5 adds vserver cifs domain preferred-dc configuration
validation. The parameter 'skip-config-validation' is mandatory
for 'cifs-domain-preferred-dc-add' now and is set to false,
i.e. an invalid config will raise early.
Change-Id: I5eb97ba1b29ad24b296e12064f81eb93533c6b99
Closes-Bug: 1887643
(cherry picked from commit 3057d0643e)
(cherry picked from commit 7248532de8)
(cherry picked from commit 6ad361a185)