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/sensors/module.json.captured

@@ -0,0 +1,69 @@
+{
+  "module": "sensors",
+  "version": "1",
+  "capabilities": [
+    "package-manager",
+    "service-manager"
+  ],
+  "tools": [
+    "sensors_summary",
+    "sensors_temperatures",
+    "sensors_fans",
+    "sensors_drives",
+    "sensors_faults",
+    "sensors_health"
+  ],
+  "resources": [
+    {
+      "id": "smartmontools",
+      "type": "package",
+      "package": "smartmontools"
+    },
+    {
+      "id": "drives",
+      "type": "process",
+      "name": "sensors-drives",
+      "artifact": "tools",
+      "run": [
+        "./sensors",
+        "drives"
+      ],
+      "health": {
+        "kind": "unit"
+      }
+    },
+    {
+      "id": "watch",
+      "type": "process",
+      "name": "sensors-watch",
+      "artifact": "tools",
+      "run": [
+        "./sensors",
+        "watch"
+      ],
+      "health": {
+        "kind": "tool",
+        "tool": "sensors_health",
+        "interval": "60s",
+        "timeout": "10s",
+        "looks": 2,
+        "grace": "60s"
+      }
+    }
+  ],
+  "build": {
+    "artifacts": [
+      {
+        "name": "tools",
+        "kind": "bundle",
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/sensors",
+        "binary": "sensors",
+        "loads": [
+          "sensors"
+        ]
+      }
+    ]
+  }
+}