tests: Fix syntax in iSCSI auth/secret tests

tests: Fix syntax in iSCSI auth/secret tests

While working on the tests for the secret initialization vector, I found
that the existing iSCSI tests were lacking in how they defined the IQN.
Many had IQN's of just 'iqn.1992-01.com.example' for one disk while using
'iqn.1992-01.com.example/1' for the second disk (same for hostdevs - guess
how they were copied/generated).

Typically (and documented this way), IQN's would include be of the form
'iqn.1992-01.com.example:storage/1' indicating an IQN using "storage" for
naming authority specific string and "/1" for the iSCSI LUN.

So modify the input XML's to use the more proper format - this of course
has a ripple effect on the output XML and the args.

Also note that the "%3A" is generated by the virURIFormat/xmlSaveUri
to represent the colon.

Signed-off-by: John Ferlan <jferlan@redhat.com>
(cherry picked from commit dd1400280eb0fcd38906b17a9341ac9fe6317498)