notifications-backend: migrated to use new auth services

Co-authored-by: Fredrik Adelöw <freben@gmail.com>
Co-authored-by: Carl-Erik Bergström <cbergstrom@spotify.com>
Co-authored-by: blam <ben@blam.sh>
Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

plugins/notifications-node/package.json

@@ -27,6 +27,7 @@
     "postpack": "backstage-cli package postpack"
   },
   "devDependencies": {
+    "@backstage/backend-test-utils": "workspace:^",
     "@backstage/cli": "workspace:^",
     "@backstage/test-utils": "workspace:^",
     "msw": "^1.0.0"