qemuxmlconftest: Add 'latest' version of 'launch-security-sev*' originally using 6.0.0
The 'launch-security-sev' and
'launch-security-sev-missing-platform-info' tests run agains the
qemu-6.0.0 caps which were manually doctored to support SEV.
Since we now have the '+amdsev' variant dumped from a more modern qemu
add another invocation of the tests.
The only relevant difference in the output data is 'cbitpos' being '51'
on the new platform, for the test case which explicitly doesn't
configure it.
Signed-off-by: Peter Krempa <pkrempa@redhat.com> Reviewed-by: Pavel Hrdina <phrdina@redhat.com>