test(xatu): reuse lint findings fixture

src/xatu/testdata/lint_findings.nix

@@ -1,5 +1,9 @@
-{
+let
+  support = "support";
+  primary = support;
+in {
   package = package;
   from = pkgs.from;
   url = https://example.com;
+  ordered = primary;
 }