virsh_uri: Change TestError to TestNAError

Following lead of similar tests that use the EXAMPLE.COM
checking, use TestNAError rather than TestError to result
in SKIP instead of ERROR for test

Signed-off-by: John Ferlan <jferlan@redhat.com>
virt.tests: fix typo in unattended_install test

Signed-off-by: Xu Tian <xutian@redhat.com>