CA-139258: Fix functional tests on iSCSI SR
CA-139258: Fix functional tests on iSCSI SR

Raise an exception from within xencert when iscsiadm discovery fails and
abort any further tests.

Signed-off-by: Siddharth Vinothkumar <dfecda33490a98eb9acd390f514dd6b90713a050@citrix.com>
Reviewed-by: Mate Lakat <c9738e4c994fd7ce84ba48d79abf74ae257dc234@citrix.com>

xenserver/xencert,chandrikas/xencert,chandrikas/xencert,vivekkumac/xencert,xenserver/xencert,vivekkumac/xencert,chandrikas/xencert,xenserver/xencert,vivekkumac/xencert