The actors for the Review Checker need prefs to be set to be enabled, which wasn't happening with the current Nimbus fallbacks. - Switch to using `setPref` for shopping2023 enabled and integrateSidebar so actor enablePreference handlers will work. - Remove unused control listeners for shopping2023. - Listen for pref changes instead of Nimbus changes in ShoppingUtils for enabling and disabling the features. Differential Revision: https://phabricator.services.mozilla.com/D245500