nixos/vector: Tweak journald/clickhouse test to check the absence of

zero results instead

Fixes small race-condition between database being ready and Vector being
able to log into it and then the result number changing

nixos/tests/vector/journald-clickhouse.nix

@@ -199,11 +199,11 @@ in
         )
 
       clickhouse.fail(
-        "cat ${selectQuery} | clickhouse-client --user vector --password helloclickhouseworld | grep 2"
+        "cat ${selectQuery} | clickhouse-client --user vector --password helloclickhouseworld | grep -v 0"
       )
 
       clickhouse.wait_until_succeeds(
-        "cat ${selectQuery} | clickhouse-client --user grafana --password helloclickhouseworld2 | grep 2"
+        "cat ${selectQuery} | clickhouse-client --user grafana --password helloclickhouseworld2 | grep -v 0"
       )
     '';
 }