tests: ensure that image validation will not cure the corruption

Since
    commit cfce1091d55322789582480798a891cbaf66924e
    Author: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
    Date:   Tue Jul 18 12:44:29 2023 +0200
    parallels: Image repairing in parallels_open()
there is a potential pit fall with calling
    qemu-io -c "read"
The image is opened in read-write mode and thus could be potentially
repaired. This could ruin testing process.

The patch forces read-only opening for reads. In that case repairing
is impossible.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
1 file changed