chore: disable renovate dependency dashboard (#1194)

Author: chingor13

synthtool/gcp/templates/node_library/renovate.json

@@ -1,7 +1,8 @@
 {
   "extends": [
     "config:base",
-    "docker:disable"
+    "docker:disable",
+    ":disableDependencyDashboard"
   ],
   "pinVersions": false,
   "rebaseStalePrs": true,