LAVA jobs are AFAIK not useful since the read-only images landed. Since
we've disabled publishing image artifacts earlier, let's properly
disable the LAVA jobs as well.

This commit should be reverted when LAVA jobs are working and the
slowness issue was debugged.

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@huawei.com>