iotest 302: use img_info_log() helper

iotest 302: use img_info_log() helper

Instead of qemu_img_log("info", ..) use generic helper img_info_log().

img_info_log() has smarter logic. For example it use filter_img_info()
to filter output, which in turns filter a compression type. So it will
help us in future when we implement a possibility to use zstd
compression by default (with help of some runtime config file or maybe
build option). For now to test you should recompile qemu with a small
addition into block/qcow2.c before
"if (qcow2_opts->has_compression_type":

    if (!qcow2_opts->has_compression_type && version >= 3) {
        qcow2_opts->has_compression_type = true;
        qcow2_opts->compression_type = QCOW2_COMPRESSION_TYPE_ZSTD;
    }

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20211223160144.1097696-12-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>