NX: Use legacy cache

Due to the following issue nrwl/nx#28806, which we encounter in the GitHub Window Unit Test Job regularly, we have to opt-in to NX's legacy cache mechanism. That will use the file system instead of a file DB for caching.

code/nx.json

@@ -3,6 +3,7 @@
   "extends": "nx/presets/npm.json",
   "nxCloudAccessToken": "NGVmYTkxMmItYzY3OS00MjkxLTk1ZDktZDFmYTFmNmVlNGY4fHJlYWQ=",
   "defaultBase": "next",
+  "useLegacyCache": "true",
   "parallel": 8,
   "plugins": [
     {