fix: special handling of unmarshalling for invalid json dashboards (#108519)

* implement special dashboard fallback logic when dashboard data has invalid json behind feature flag

---------

Co-authored-by: Will Assis <william@williamassis.com>

pkg/services/featuremgmt/toggles_gen.json

@@ -2760,6 +2760,18 @@
         "codeowner": "@grafana/identity-access-team"
       }
     },
+    {
+      "metadata": {
+        "name": "scanRowInvalidDashboardParseFallbackEnabled",
+        "resourceVersion": "1753730899886",
+        "creationTimestamp": "2025-07-28T19:28:19Z"
+      },
+      "spec": {
+        "description": "Enable fallback parsing behavior when scan row encounters invalid dashboard JSON",
+        "stage": "experimental",
+        "codeowner": "@grafana/search-and-storage"
+      }
+    },
     {
       "metadata": {
         "name": "scopeApi",