0321 tweak

`url` and `discover` prefs stop the recommendations, the `enabled` pref hides the leftover recommended section and "Find more add-ons" button

user.js

@@ -220,6 +220,7 @@ user_pref("extensions.webservice.discoverURL", "");
 /* 0321: disable recommendations in about:addons' Extensions and Themes panes [FF68+] ***/
 user_pref("extensions.getAddons.discovery.api_url", "");
 user_pref("extensions.htmlaboutaddons.discover.enabled", false);
+user_pref("extensions.htmlaboutaddons.recommendations.enabled", false);
 /* 0330: disable telemetry
  * the pref (.unified) affects the behaviour of the pref (.enabled)
  * IF unified=false then .enabled controls the telemetry module