groups: Enable group-settings value on groups in production.

The main change is redefining ALLOW_GROUP_VALUED_SETTINGS to not
control code, but instead to instead control the configuration for
whether settings that have not been converted to use our modern UI
patterns should require system groups.

Fundamentally, it's the same for the realm/stream group-valued
settings, which don't have the new UI patterns yet.

We remove the visual hiding of the "can manage group" setting, which
was hidden only due to transitions being incomplete.

web/src/user_group_edit.js

@@ -18,7 +18,6 @@ import {$t, $t_html} from "./i18n";
 import * as ListWidget from "./list_widget";
 import * as loading from "./loading";
 import * as overlays from "./overlays";
-import {page_params} from "./page_params";
 import * as people from "./people";
 import * as scroll_util from "./scroll_util";
 import * as settings_components from "./settings_components";
@@ -198,10 +197,6 @@ function show_general_settings(group) {
         group,
     });
     update_general_panel_ui(group);
-
-    if (!page_params.development_environment) {
-        $(".can-manage-group-container").hide();
-    }
 }
 
 function update_general_panel_ui(group) {