cli: Simplify systemctl check

using the `-q` flag has the same usefulness as the shell redirecting but
is way easier to read. Therefore, let's use that.

cli/koolbox

@@ -17,7 +17,7 @@ fi
 
 # Using systemd-resolved when available
 PODMAN_NETWORK_SETTINGS=""
-if systemctl is-active systemd-resolved.service > /dev/null 2>&1; then
+if systemctl -q is-active systemd-resolved.service; then
   PODMAN_NETWORK_SETTINGS="--network host --dns 127.0.0.53"
 fi