gitlab: mutual binding between gitlab-config and gitlab-db-config

just an attempt fo fix test failure, this should not really be necessary

nixos/modules/services/misc/gitlab.nix

@@ -1310,6 +1310,7 @@ in {
     systemd.services.gitlab-config = {
       wantedBy = [ "gitlab.target" ];
       partOf = [ "gitlab.target" ];
+      bindsTo = [ "gitlab-db-config.service" ];
       path = with pkgs; [
         jq
         openssl