Adjust tests for update and workaround repos provided as ISO
I'm attempting a new approach to the update and workaround repos.
Instead of having each update test recreate them for itself -
which is slow and wastes bandwidth - the dispatcher will create
an ISO at test schedule time and pass it as ISO_2. Then the test
just mounts the ISO. This makes the necessary adjustments on the
test side.
Signed-off-by: Adam Williamson <awilliam@redhat.com>