Refresh ssh verification mechanism

Last week there was a change in how ssh_verification in done in tempest
(see I76d818bf9e1bd26b1e499464fc9213764afee279) since those mechanisms
are shared and used by Ironic's scenario test we should also update it.

Change-Id: I68e9ee3faf747697cd5f50600ecadb15972cdd48
1 file changed