ui: fix notification service in token controller (#16918)

Remove unneeded service injection. This service is not being used in
this controller and currently only exists in `main`, causing
`release/1.5.x` to break.

ui/app/controllers/settings/tokens.js

@@ -23,7 +23,6 @@ export default class Tokens extends Controller {
   @service token;
   @service store;
   @service router;
-  @service notifications;
 
   queryParams = ['code', 'state', 'jwtAuthMethod'];