tests: Copy image when unattended install failed even in the start steps

We use unattended install in test loops as an image prepare case. So
we need it copy image from nfs if the case is failed. Otherwise the
following cases in the test loop will failed because the image is not
bootable.

Signed-off-by: Yiqiao Pu <ypu@redhat.com>
shared.unattended: Update the unattended files

Update the format of unattended files. Add some commands for
Windows test enviroment prepare. Also enlarge the Windows
image size to 30G as we will install more package inside the guests.

For the RHEL guests ks, we update some package that we needed. And
start X when guest booted up.

Signed-off-by: Yiqiao Pu <ypu@redhat.com>
test.cfg: Add some sub test in unattended install

Add some sub test in unattended install.

Signed-off-by: Yiqiao Pu <ypu@redhat.com>