chore: remove unused dependencies

Remove 30 dependencies across 18 packages that have no imports in
source code and are not peer dependencies of any other dependency.

Signed-off-by: Fredrik Adelöw <freben@spotify.com>
Made-with: Cursor

plugins/search-backend/package.json

@@ -69,7 +69,6 @@
     "express": "^4.22.0",
     "lodash": "^4.17.21",
     "qs": "^6.10.1",
-    "yn": "^4.0.0",
     "zod": "^3.25.76 || ^4.0.0"
   },
   "devDependencies": {