rework victoriametrics to be more generic with test

modules/clan/victoriametrics/default.nix

@@ -0,0 +1,25 @@
+{ ... }:
+{
+  _class = "clan.service";
+  manifest.name = "Victoria Metrics";
+  manifest.description = "VictoriaMetrics: fast, cost-effective monitoring solution and time series database";
+  manifest.categories = [ "System" ];
+
+  roles.default = {
+    perInstance.nixosModule =
+      {
+        config,
+        lib,
+        ...
+      }:
+      {
+        services.victoriametrics = {
+          enable = lib.mkDefault true;
+        };
+
+        clan.core.state.victoriametrics.folders = lib.mkDefault [
+          "/var/lib/${config.services.victoriametrics.stateDir}"
+        ];
+      };
+  };
+}