qemuhotplugtest: Verify domain XML on UPDATE

qemuhotplugtest: Verify domain XML on UPDATE

Just like we check the resulting domain XML after ATTACH and
DETACH, we should do the same after UPDATE action. This is as
simple as calling testQemuHotplugCheckResult() and providing
missing XMLs. For those test cases where no change is done, we
can just make the expected XML a symlink to the input XML.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Kristina Hanicova <khanicov@redhat.com>