Run a health check before the test, as the test depends on CoreDNS being
healthy, and previous tests might disturb the cluster.
Also refactor by using watch instead of retries, make pods terminate
fast.
Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com>
More specifically, pick up `/etc/resolv.conf` contents by default when
in container mode, and use that as a base resolver for the host DNS.
Fixes#8303
Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com>
