Judge tests that read another repository against what the check clones, never the desktop's checkout (issue 432)

Tests that read ../../../mesh-catalog or ../../../mesh-host gave a verdict
that depended on what sat beside the checkout: a stale or dirty sibling
failed them on a desktop, and a missing one skipped them unseen. They now
read the clone the build seat puts in MESH_CHECK_BESIDE, failing when it is
absent there, and elsewhere a copy captured at a named commit.

The skip had hidden that the builder test read a module retired by ADR 0190.
The systemd reading test no longer counts the machine's own environment.d.

testdata/beside/mesh-catalog/modules/dbus/module.json.captured

@@ -0,0 +1,67 @@
+{
+  "module": "dbus",
+  "version": "1",
+  "capabilities": [
+    "package-manager",
+    "service-manager"
+  ],
+  "claims": [
+    {
+      "name": "node-message-bus",
+      "scope": "node"
+    }
+  ],
+  "emits": [
+    "bus.stalled",
+    "bus.recovered",
+    "bus.restarted",
+    "service.appeared",
+    "service.left",
+    "policy.denied"
+  ],
+  "tools": [
+    "dbus_names",
+    "dbus_introspect",
+    "dbus_monitor",
+    "dbus_check",
+    "dbus_health"
+  ],
+  "resources": [
+    {
+      "id": "dbus",
+      "type": "package",
+      "package": "dbus"
+    },
+    {
+      "id": "broker",
+      "type": "package",
+      "package": "dbus-broker"
+    },
+    {
+      "id": "broker-units",
+      "type": "package",
+      "package": "dbus-broker-units"
+    },
+    {
+      "id": "system-bus",
+      "type": "service",
+      "unit": "dbus-broker.service",
+      "state": "running"
+    }
+  ],
+  "build": {
+    "artifacts": [
+      {
+        "name": "tools-go",
+        "kind": "bundle",
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/dbus-tools",
+        "binary": "dbus-tools",
+        "loads": [
+          "dbus-tools"
+        ]
+      }
+    ]
+  }
+}