checks: Disable syncthing test for now

Syncthing is currently being migrated and we can look at the test again
once we migrated.
It recently got changes upstream which might explain the spurious test
failures.

checks/flake-module.nix

@@ -53,7 +53,6 @@ in
               dummy-inventory-test = import ./dummy-inventory-test nixosTestArgs;
               borgbackup = import ./borgbackup nixosTestArgs;
               data-mesher = import ./data-mesher nixosTestArgs;
-              syncthing = import ./syncthing nixosTestArgs;
             }
             // lib.optionalAttrs (pkgs.stdenv.hostPlatform.system == "aarch64-linux") {
               # for some reason this hangs in an odd place in CI, but it works on my machine ...