settings: Fix exception on updating bot_creation_policy.

This initializes the bot_creation_policy_values after the page
is loaded.

Previously we initialize these values in `settings.js` when settings page
is loaded at least once, so if we open two tabs, one(1) in which we
haven't opened the settings page yet and if in another tab (2) we
update the `bot_creation_policy` value, then because of the event
which calls `settings_bots.update_bot_permissions_ui` causes exception
in (1) because `bot_creation_policy_values` isn't initialized yet.

Fixes: #8852.

static/js/settings.js

@@ -122,7 +122,6 @@ function _setup_page() {
     }());
 
     setup_settings_label();
-    settings_bots.setup_bot_creation_policy_values();
 
     var settings_tab = templates.render('settings_tab', {
         full_name: people.my_full_name(),

static/js/settings_ui.js

@@ -16,6 +16,8 @@ function _initialize() {
         failure: i18n.t("Save failed"),
         saving: i18n.t("Saving"),
     };
+
+    settings_bots.setup_bot_creation_policy_values();
 }
 
 exports.initialize = function () {